synth: receive/send dx7 params as sysex

[bfredl]

This works to edit a dx7 patch on the deluge using e.g. the Dexed desktop app, although it is a bit of a mess to setup.

[github-actions]

Test Results

107 tests  ±0   107 ✅ ±0   0s ⏱️ ±0s
 16 suites ±0     0 💤 ±0 
 16 files   ±0     0 ❌ ±0 

Results for commit 0c781f0. ± Comparison against base commit 1f82d07.

♻️ This comment has been updated with latest results.

[sapphire-arches]

would be good to add docs on how to set this up to the dx7 markdown.

[m-m-adams]

these instructions should probably go to midi port 3 - we don't implement midi sysex stream interruption so I think it could cause bugs if you're playing notes and editing at the same time

[m-m-adams]

This has a bunch of conflicts now - are you still working on it?

[bfredl]

Rebased and changed preferred sysex port to "Deluge MIDI 3"

[mweigt]

First of all: Thank you for the fantastic Work! Enabling DX7 emulation on Deluge is an incredible added value!

As testing was requested: Just jammed for one hour using dexed as sound control surface while playing a track on the deluge. Everything seems to work.

Some nits :

• I have to actually enter a single parameter sub-menu (i.e. "algorithm" or "sync") for the "learn" assign midi channel to work, not just the "DX7 parameters" menu. That might be the intended behaviour, but the Doc is a bit ambiguous here.
• I have to activate midi follow mode for the deluge to react to dexed param changes. Again, this is probably the (currently) intended behaviour, but the docs could be interpreted as this being optional.
• Is there/will there be a way to assign a fixed channel without using midi follow?
• When using dexed to control the deluge, only one paramter seems to be sent at each edit: switching to a different patch on dexed is not reflected on the deluge. I do not know if dexed is not sending the data or deluge not recieving/processing this.
• Is there/will there be a way to additionally learn single parameters to normal midi CCs?