Ffsubsync

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* Fix corner case bug that occurred when multiple sync attempts were scored the same;

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* Attempt speech extraction from subtitle tracks embedded in video first before using VAD;

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* Hotfix for test archive creation bug;

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* Add ability to merge synced and reference subs into bilingual subs when reference is srt;

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* Fix bug when handling ass/ssa input, this format should work now;

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* Better detection of text file encodings;
* ASS / SSA functionality (but currently untested);
* Allow serialize speech with --serialize-speech flag;
* Convenient --make-test-case flag to create test cases when filing sync-related bugs;
* Use utf-8 as default output encoding (instead of using same encoding as input);
* More robust test framework (integration tests!);