Document everything

[sikthehedgehog]

And I'm not talking about the severe lack of comments in the source code :v

There's a lot of behavior that isn't properly documented, like the initial state of the channels when a track starts, the annoying quirk where loading a FM instrument resets volume but for PSG it doesn't, etc. All of this is extremely important to know if you're making a tool, and nobody should be expected to know it ahead of time (or even after the fact, don't force people to memorize everything!).