Adding cython v0.20.2 in third-party.

third_party/cython/src/Cython/Plex/__init__.py

Index: third_party/cython/src/Cython/Plex/__init__.py
diff --git a/third_party/cython/src/Cython/Plex/__init__.py b/third_party/cython/src/Cython/Plex/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..22b9bba3b8cf669336dc71d3531d0e77c02c0e30
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+++ b/third_party/cython/src/Cython/Plex/__init__.py
@@ -0,0 +1,40 @@
+#=======================================================================
+#
+#   Python Lexical Analyser
+#
+#=======================================================================
+
+"""
+The Plex module provides lexical analysers with similar capabilities
+to GNU Flex. The following classes and functions are exported;
+see the attached docstrings for more information.
+
+   Scanner          For scanning a character stream under the
+                    direction of a Lexicon.
+
+   Lexicon          For constructing a lexical definition
+                    to be used by a Scanner.
+
+   Str, Any, AnyBut, AnyChar, Seq, Alt, Opt, Rep, Rep1,
+   Bol, Eol, Eof, Empty
+
+                    Regular expression constructors, for building pattern
+                    definitions for a Lexicon.
+
+   State            For defining scanner states when creating a
+                    Lexicon.
+
+   TEXT, IGNORE, Begin
+
+                    Actions for associating with patterns when
+        creating a Lexicon.
+"""
+
+from Actions import TEXT, IGNORE, Begin
+from Lexicons import Lexicon, State
+from Regexps import RE, Seq, Alt, Rep1, Empty, Str, Any, AnyBut, AnyChar, Range
+from Regexps import Opt, Rep, Bol, Eol, Eof, Case, NoCase
+from Scanners import Scanner
+
+
+