Cleaned up the mess after some historical revisionism.
Added GUI, fixed some adlib parameters.
Opps, forgot a bunch of `add`s! Additional UI work, clean up of MidiDisp.
Begin to move complexity out of Adlib Instrument, into OPLDriver this time.

OPLDriver clients don't need to write bit-packed registers all at once.
Added a OPL register display for debugging.
Added a method for setting parameters by logical value on Instruments.
Added channel vibrato and tremolo parameters.
Changed OPLDriver volume parameter to mfg.'s weird inverted value.
Added Tremolo and Vibrato depth to OPLDriver
Hooked up tremolo/vibrato depth to adlib instrument
Added tremolo and vibrato depth to display
Theoretically added waveform select. Can't hear difference.
Disabled debug instrument.
Added adlib pitch bend.
Shorter names, less typing, potentially 8.3 compatible.
Smarter redraw, TextMode as singleton.
Parameter enums, reordered some. Added channel to UI.
Can edit parameters from the gui
Consolidated TextMode internals
Moved TextMode to BIOS functions, combined with Cursor
Made TextScreen non-exclusive again.
Added text screen paging.
Values from gui no longer scaled.
Added animated screensaver.