Remove debug lines
Update supersaw synth design:

* Add rplf to ugen chain
* Introduce new _s version of supersaw with now filter and simpler design
Use new named thread functionality in comps beats example
Add license info to synth-designs file.
Re-order dsaw arg order for consistency.
Started work on synth information classes for docs and validation.
Improve fm synth design - add slide args for both div and depth

- replaces mod_slide arg
Start fleshing out synth information
Fix bug in Node's on_destroyed method:

don't call all callbacks if state is already destroyed, just call the
callback itself. Node already will call callbacks when destroyed.
ensure state is set to :destroyed before calling on_destroyed_callbacks
Kill ChordGroup node when all containing subsides are destroyed.
move to snake_cased names for sample synths
specify :amp arg for :amp validation!
Reference new snake_case sample synth names
Wire up synth arg validation functionality (still needs fleshing out)
Teach trigger and control args to handle symbols for note names.
Breaking Change - rename with_volume to set_volume!
Rename debug! and debug_off! to set_debug_on! and set_debug_off!
Breaking change: rename with_tempo to set_tempo!
add :modulatable metadata to synth info