Submerge 3.3.2

- Ready for macOS Sierra.
- FFmpeg updated to the 3.1.2 "Laplace" release.
- New algorithm for calculating the subtitle bounding box. Shouldn't cut the lower parts for some fonts.
- Editing a WebVTT file outside Submerge now works as expected.
- Another try at getting Hebrew and Arabic subtitles to render correctly.
- Subtitle file parsing approved for some special character combos.
- Fixed a potential crash bug.