Things to do:
- Implement parsing of sysexes chopped into several "packets".
- Add support for type 2 SMF files.
- Add support for SMPTE time.
- Rework removal of tempo changes. Right now there is one scenario that is broken - when
you have two tempo-related events at the end of the song (i.e. there are no events following),
removing one of these tempo-related events will remove both tempo changes.
- Add a way to force some particular tempo during playback and ignore the following tempo changes.