Ffsubsync

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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!);

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* Try to correct for framerate differences by picking best framerate ratio;

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* Revert changes from 0.2.9 now that srt parses weird timestamps robustly;

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* Revert changes from 0.2.12 (caused regression on Windows);

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* Bump min required scikit-learn to 0.20.4;

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* Clear O_NONBLOCK flag on stdout stream in case it is set;