Add CTR encryption.

- Added ContentEncAESSettings, AESSettingsCipherMode,
  AESSettingsCipherInitData elements to the parser and muxer.
- Changed ParseContentEncodingsEntry, ParseContentEncodingEntry,
  and ParseEncryptionEntry to use PasreElementHeader.
- Added ParseContentEncAESSettingsEntry function.
- PS6 removed AESSettingsCipherInitData.
- PS9 Addressed comments, Fixed some LINT issues, and converted
  mkvwriter.h/.cpp to Unix line endings.
- PS10 Addressed comments.

Change-Id: I9d96a0c194f74a6c9bf0001aa0286196e410f07e

mkvmuxerutil.hpp

@@ -75,7 +75,7 @@ uint64 WriteVoidElement(IMkvWriter* writer, uint64 size);
 
 // Returns the version number of the muxer in |major|, |minor|, |build|,
 // and |revision|.
-void GetVersion(int32& major, int32& minor, int32& build, int32& revision);
+void GetVersion(int32* major, int32* minor, int32* build, int32* revision);
 
 }  //end namespace mkvmuxer