Restructure server code to support both native and external scsynth
servers:

* Native server code doesn't quite work yet
* Need to remove debug messages
Fix start-server script to work with new scsynth structure
Use more appropriate FFI blocking declaration
Stop using global variables
Add some more API docs
Incubate blue_monday example as it doesn't currently perform well on RP
Update docs in Qt app
Only store true or false in arg_check thread local
Add new thread local value viewing functions:

* current_synth
* current_transpose
* current_debug
* current_arg_checks
stop scsynth dumping all OSC messages
Fix syntax errors in doc additions
Don't pull in native file as it's still incomplete.
Merge branch 'master' into split-docs-gen2