Feature: Visualization api

[BleuLlama]

I have a bunch of visualizers from my iOS mod player that i'd love to fly in to this codebase. Perhaps a button to switch the pattern view into a visualizer view (like the way it is replaced with sample editor, etc.

It'd be great to have a visualizer api, with a few entry points:

• initialization/startup
• shutdown
• poll for screen update

It would need to have access to some bits of data to be able to do fun stuff with the content:

• graphics context/bitmap to render into
• current song metadata
• pattern, position, speed, tempo, number of voices, etc
• for each voice: current volume, waveform, pan position, frequency

I'm sure all of this is in there somewhere, as it's currently used for the main display.

I think a great first-version would be a single visualizer built in to the codebase... in fact all visualizers can be compiled-in. they don't need to be plugins at all.

Perhaps a way to have one or two configuration values using the exisiting widgets in the future would be nice as well. (select a number using up/dn buttons, 7 segment display, etc)

I haven't looked through the code at all yet to begin to delve into this myself, but i might if nothing is planned along these lines....