Allow SCL to MTS script to work with GM Synth

[ghost]

I note that ACE fluidsynth allows for scala tuning via the lua script but it would be nice if your own synth could offer the same.

[x42]

The issue is deeper.

ACE fluidsynyth save/restores the state (sf2 file, chorus, reverb etc), so it can also save custom tuning.

GMsynth.lv2 is intentionally simple and stateless. Just like with a GM hardware synth, a power-cycle resets the whole synth.

So custom tuning cannot be saved/restored. In context of a DAW session that means that every time you open the session you would have to apply the tuning. Patch/program settings are lost as well, but DAWs/Sequencers replay those as part of a MIDI track.