- added `25xx` and `26xx` effects in Neo Geo platform for
envelope period slides
- added `3xxx` and `4xxx` effects in C64 for fine duty/cutoff control
- made home/end keys work
- deleting a single note will delete related instrument value as well
- fix instrument value input when there are less than 16 instruments
- added `Cxxx` effect for mid-song Hz change
- possibly fix a hang when using multiple sound chips
- reduce PC Engine CPU usage