Feat/env follow trigger

Note: This breaks existing SATIE code, as makeSynthDef's signature is modified.

Note2: You will need NodeSnapshot.quark. Quark.install('NodeSnapshot') should do the job.

Here's a proposition for support of metering/analysis plugins in SATIE. In short, another set of plugins that are wrapped in the Factiory class, they grab the input signal and don't return any signal, instead, they send OSC messages back to the client, which then must be caught and dispatched.

There are two plugins included: envTrigger and envlopeFollower which also demonstrate two different ways of sending message from a Synth back to the client. Currently, we catch the messages, massage with NodeSnapshot and print some info to the PostBuffer.

You can test it with this snippet. The post-bus insert is unimplemented yet and I have not tested using several analysis plugins in the same signal chain, but theoretically it should be working. Edit: for now post-bus is not planned.

I will pursue in this direction until the demo of April 12. We can discuss this and eventually merge when things are clear and tested.

Known problems:

• It works only with scsynth, see comment on SATIE-173 for details.
• Watch out for SynthDef arguments collisions in your plugins.

Edit: the merge request that fixes the names in supernova's queryTree is still pending so in order to test it the comment about scsynth still holds

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