Update XZ Utils to 5.0.4 (third_party)

README

 
 XZ Utils
 ========
 
     0. Overview
     1. Documentation
        1.1. Overall documentation
-       1.2. Documentation for command line tools
+       1.2. Documentation for command-line tools
        1.3. Documentation for liblzma
     2. Version numbering
     3. Reporting bugs
     4. Translating the xz tool
     5. Other implementations of the .xz format
     6. Contact information
 
 
 0. Overview
 -----------
 
-    XZ Utils provide a general-purpose data compression library and
-    command line tools. The native file format is the .xz format, but
+    XZ Utils provide a general-purpose data-compression library plus
+    command-line tools. The native file format is the .xz format, but
     also the legacy .lzma format is supported. The .xz format supports
-    multiple compression algorithms, which are called "filters" in
+    multiple compression algorithms, which are called "filters" in the
     context of XZ Utils. The primary filter is currently LZMA2. With
     typical files, XZ Utils create about 30 % smaller files than gzip.
 
     To ease adapting support for the .xz format into existing applications
     and scripts, the API of liblzma is somewhat similar to the API of the
-    popular zlib library. For the same reason, the command line tool xz
-    has similar command line syntax than that of gzip.
+    popular zlib library. For the same reason, the command-line tool xz
+    has a command-line syntax similar to that of gzip.
 
-    When aiming for the highest compression ratio, LZMA2 encoder uses
+    When aiming for the highest compression ratio, the LZMA2 encoder uses
     a lot of CPU time and may use, depending on the settings, even
-    hundreds of megabytes of RAM. However, in fast modes, LZMA2 encoder
+    hundreds of megabytes of RAM. However, in fast modes, the LZMA2 encoder
     competes with bzip2 in compression speed, RAM usage, and compression
     ratio.
 
     LZMA2 is reasonably fast to decompress. It is a little slower than
     gzip, but a lot faster than bzip2. Being fast to decompress means
     that the .xz format is especially nice when the same file will be
     decompressed very many times (usually on different computers), which
     is the case e.g. when distributing software packages. In such
     situations, it's not too bad if the compression takes some time,
     since that needs to be done only once to benefit many people.
 
     With some file types, combining (or "chaining") LZMA2 with an
-    additional filter can improve compression ratio. A filter chain may
-    contain up to four filters, although usually only one two is used.
+    additional filter can improve the compression ratio. A filter chain may
+    contain up to four filters, although usually only one or two are used.
     For example, putting a BCJ (Branch/Call/Jump) filter before LZMA2
     in the filter chain can improve compression ratio of executable files.
 
     Since the .xz format allows adding new filter IDs, it is possible that
     some day there will be a filter that is, for example, much faster to
     compress than LZMA2 (but probably with worse compression ratio).
     Similarly, it is possible that some day there is a filter that will
     compress better than LZMA2.
 
     XZ Utils doesn't support multithreaded compression or decompression
@@ skipping 22 matching lines @@
     THANKS              Incomplete list of people who have helped making
                         this software
     NEWS                User-visible changes between XZ Utils releases
     ChangeLog           Detailed list of changes (commit log)
     TODO                Known bugs and some sort of to-do list
 
     Note that only some of the above files are included in binary
     packages.
 
 
-1.2. Documentation for command line tools
+1.2. Documentation for command-line tools
 
-    The command line tools are documented as man pages. In source code
+    The command-line tools are documented as man pages. In source code
     releases (and possibly also in some binary packages), the man pages
     are also provided in plain text (ASCII only) and PDF formats in the
     directory "doc/man" to make the man pages more accessible to those
     whose operating system doesn't provide an easy way to view man pages.
 
 
 1.3. Documentation for liblzma
 
     The liblzma API headers include short docs about each function
     and data type as Doxygen tags. These docs should be quite OK as
     a quick reference.
 
     I have planned to write a bunch of very well documented example
     programs, which (due to comments) should work as a tutorial to
     various features of liblzma. No such example programs have been
     written yet.
 
     For now, if you have never used liblzma, libbzip2, or zlib, I
-    recommend learning *basics* of zlib API. Once you know that, it
-    should be easier to learn liblzma.
+    recommend learning the *basics* of the zlib API. Once you know that,
+    it should be easier to learn liblzma.
 
         http://zlib.net/manual.html
         http://zlib.net/zlib_how.html
 
 
 2. Version numbering
 --------------------
 
     The version number format of XZ Utils is X.Y.ZS:
 
       - X is the major version. When this is incremented, the library
         API and ABI break.
 
-      - Y is the minor version. It is incremented when new features are
-        added without breaking existing API or ABI. Even Y indicates
-        stable release and odd Y indicates unstable (alpha or beta
-        version).
+      - Y is the minor version. It is incremented when new features
+        are added without breaking the existing API or ABI. An even Y
+        indicates a stable release and an odd Y indicates unstable
+        (alpha or beta version).
 
-      - Z is the revision. This has different meaning for stable and
+      - Z is the revision. This has a different meaning for stable and
         unstable releases:
+
           * Stable: Z is incremented when bugs get fixed without adding
-            any new features.
+            any new features. This is intended to be convenient for
+            downstream distributors that want bug fixes but don't want
+            any new features to minimize the risk of introducing new bugs.
+
           * Unstable: Z is just a counter. API or ABI of features added
             in earlier unstable releases having the same X.Y may break.
 
       - S indicates stability of the release. It is missing from the
-        stable releases where Y is an even number. When Y is odd, S
+        stable releases, where Y is an even number. When Y is odd, S
         is either "alpha" or "beta" to make it very clear that such
         versions are not stable releases. The same X.Y.Z combination is
-        not used for more than one stability level i.e. after X.Y.Zalpha,
+        not used for more than one stability level, i.e. after X.Y.Zalpha,
         the next version can be X.Y.(Z+1)beta but not X.Y.Zbeta.
 
 
 3. Reporting bugs
 -----------------
 
     Naturally it is easiest for me if you already know what causes the
     unexpected behavior. Even better if you have a patch to propose.
     However, quite often the reason for unexpected behavior is unknown,
     so here are a few things to do before sending a bug report:
@@ skipping 15 matching lines @@
          using gdb:
            $ gdb /path/to/app-binary   # Load the app to the debugger.
            (gdb) core core   # Open the coredump.
            (gdb) bt   # Print the backtrace. Copy & paste to bug report.
            (gdb) quit   # Quit gdb.
 
     Report your bug via email or IRC (see Contact information below).
     Don't send core dump files or any executables. If you have a small
     example file(s) (total size less than 256 KiB), please include
     it/them as an attachment. If you have bigger test files, put them
-    online somewhere and include an URL to the file(s) in the bug report.
+    online somewhere and include a URL to the file(s) in the bug report.
 
     Always include the exact version number of XZ Utils in the bug report.
     If you are using a snapshot from the git repository, use "git describe"
     to get the exact snapshot version. If you are using XZ Utils shipped
     in an operating system distribution, mention the distribution name,
     distribution version, and exact xz package version; if you cannot
     repeat the bug with the code compiled from unpatched source code,
     you probably need to report a bug to your distribution's bug tracking
     system.
 
 
 4. Translating the xz tool
 --------------------------
 
     The messages from the xz tool have been translated into a few
     languages. Before starting to translate into a new language, ask
-    the author that someone else hasn't already started working on it.
+    the author whether someone else hasn't already started working on it.
 
     Test your translation. Testing includes comparing the translated
     output to the original English version by running the same commands
     in both your target locale and with LC_ALL=C. Ask someone to
     proof-read and test the translation.
 
     Testing can be done e.g. by installing xz into a temporary directory:
 
         ./configure --disable-shared --prefix=/tmp/xz-test
         # <Edit the .po file in the po directory.>
         make -C po update-po
         make install
         bash debug/translations.bash | less
         bash debug/translations.bash | less -S  # For --list outputs
 
     Repeat the above as needed (no need to re-run configure though).
 
     Note especially the following:
 
       - The output of --help and --long-help must look nice on
-        a 80-column terminal. It's OK to add extra lines if needed.
+        an 80-column terminal. It's OK to add extra lines if needed.
 
       - In contrast, don't add extra lines to error messages and such.
         They are often preceded with e.g. a filename on the same line,
         so you have no way to predict where to put a \n. Let the terminal
         do the wrapping even if it looks ugly. Adding new lines will be
         even uglier in the generic case even if it looks nice in a few
         limited examples.
 
       - Be careful with column alignment in tables and table-like output
         (--list, --list --verbose --verbose, --info-memory, --help, and
@@ skipping 67 matching lines @@
 
     If you have questions, bug reports, patches etc. related to XZ Utils,
     contact Lasse Collin <lasse.collin@tukaani.org> (in Finnish or English).
     I'm sometimes slow at replying. If you haven't got a reply within two
     weeks, assume that your email has got lost and resend it or use IRC.
 
     You can find me also from #tukaani on Freenode; my nick is Larhzu.
     The channel tends to be pretty quiet, so just ask your question and
     someone may wake up.