Fix the book build script, and regenerate the book (add to*Case note)

scripts/convert_book.dart

Index: scripts/convert_book.dart
diff --git a/scripts/convert_book.dart b/scripts/convert_book.dart
index 642ee505cba0c789087082c7eb2e9064886d6232..e08dbd0b60039c1381387f2b4af1be7d291ac970 100755
--- a/scripts/convert_book.dart
+++ b/scripts/convert_book.dart
@@ -1,7 +1,7 @@
 #!/usr/bin/env dart
 
 import 'dart:io';
-import 'dart:async';
+import 'package:path/path.dart' as path;
 
 Directory outputDir;
 
@@ -26,7 +26,7 @@ convertFile(String fileName) {
   var start = contents.indexOf(r'<div class="navheader">');
   var end = contents.lastIndexOf(r'</body></html>');
   var body = contents.substring(start, end);
-  var filenameOnly = new Path(fileName).filename;
+  var filenameOnly = path.basename(fileName);
 
   writeFile(filenameOnly, title, body);
 }
@@ -34,7 +34,7 @@ convertFile(String fileName) {
 writeFile(String fileName, String title, String body) {
   var out = new File('${outputDir.path}/${fileName}');
   out.writeAsStringSync(frontMatter(title));
-  out.writeAsStringSync(body, mode: FileMode.APPEND, encoding: Encoding.UTF_8);
+  out.writeAsStringSync(body, mode: FileMode.APPEND);
 }
 
 checkDir(Directory dir) {
@@ -61,4 +61,4 @@ main() {
       .map((f) => f.path)
       .where((name) => name.endsWith(".html"))
       .forEach((name) => convertFile(name));
-}
+}