TODO

UI

* add help screen


PLAYBACK

* add channel muting & dimming (+ solo)
* add auto-volume reduction
* implement volume ramping, need to decode the next tick in advance?


Notes about the test modules
----------------------------

legend_of_faerghail - this is the only SoundTracker module (15 samples)

killing road - play pattern backwards trick (pattern break & position jump
commands on the same row)

coffee blues - reverse playback & jumps stresstest

condom corruption - correct handling of pattern break and pattern delay
in the same row (middle breakdown), plus effects during pattern delay

canalgreen - correct handling of pattern delay & pattern loop commands in the
intro & fx processing during pattern delay. sample swap at the very end.

living insanity - lots of delay note and retrigger note commands

kaviar - the intro turns the filter on

melon - nested pattern loops at songpos 40



BUGS
----

butterfly-syndrome:
    pos 8, row 24: slap bass sounds weird (should fade in from zero volume?)