Add MIDI Support

[NewCreature]

Since Allegro 5 doesn't include a MIDI add-on, we need to use a 3rd party add-on or develop our own. I am leaning toward making an Allegro 5 MIDI add-on. It should be fairly easy to convert Allegro 4's MIDI drivers into an add-on (Android and iOS support will need to be developed).

[NewCreature]

MIDI output support is now working on Unix/Linux, Windows, and MacOS. MIDI input support still needs to be added.

[ZoriaRPG]

Todd, does the old AG4 MIDI/Digi stuff not work at all, or was this just to add new/better MIDI on top of that?

This was a key component that has stalled me from trying to start this conversion, although time/finishing current version is another major factor, but as soon as 2.55 is done, I wanted to try porting it.

I'd just prefer not to need to futz with new and different MIDI, when the AG4 stuff works just fine, and changing our MIDI stuff would be a gigantic overhaul.

[NewCreature]

I just committed a fix to re-enable the DIGMID driver. I haven’t tested it, but it should theoretically work since it’s built atop the Allegro 4 sound routines.