Add VCV modular synth support

[oubiwann]

Features / Tasks

• [x] Investigate interop to determine if any new MIDI CC messages need to be supported
• [x] Experiment with existing MIDI CC support to see if any VCV Rack-specific convenience functions / macros are warranted
• [x] Add the ability to send realtime messages to the Go midiserver (and thus to VCV Rack)
• [x] https://github.com/ut-proj/midiserver/issues/26
• [x] #41
• [ ] #42

Resourrces

VCV is a free, open source modular synthesis framework (Eurorack emulator):

• https://vcvrack.com/
• https://vcvrack.com/manual/
• https://library.vcvrack.com/
• http://www.studiobrootle.com/best-vcv-rack-modules/

Specific support: MIDI control of the synth. See the MIDI plugins for more details:

• https://library.vcvrack.com/?query=&brand=VCV&tag=MIDI&license=free

Original issue created here:

• https://github.com/ut-proj/undertone/issues/65

[oubiwann]

I'm going to turn this into an epic, since there's a fair amount that needs to be done in order to support useful control of VCV Rack (with LFE as a compositional tool for the modular synth).

[oubiwann]

I've performed basic VCV control from LFE today using this demo patch:

• https://github.com/forgotten-tones/vcv/blob/main/patches/midi/lfe-undermidi-00.vcv

[oubiwann]

This got closed automatically -- reopening ....