reduce nesting
extract function _sub_all from GRSpec.sym_to_prop
extract function _conj from GRSpec.to_canon
new method: GRSpec.evaluate
add auxiliary initial state to Mealy machine

This creates an initial state in addition to the strategy states loaded from the result of gr1c.
This implements the machine's reaction to the initial environment inputs[k=0], where k the time sequence index.
comment unused variable
bugfix: extra && when single AP
fix synth.sys_state_mutex docstr
Merge branch 'master' of https://github.com/tulip-control/tulip-control