remove previous creation of initial states

which inferred initial states from keeping track of states seen during transition parsing.
convert transition systems to GR(1) using int-valued variable

Instead of one bool variable for each state of the TS,
a single int-valued variable (named 'loc') is used.
Implemented for gr1c.

Selection between boolean or int representation of states is available using the new arg bool_states of function: synth.synthesize
rename variable trans -> sys_trans
bugfix: use state_ids for dead-ends
combine synth methods: sys_trans_from_ts, sys_trans_from_open_ts
rm function: synth.sys_state_mutex, rename: pure_mutex -> mutex
Merge branch 'master' of https://github.com/tulip-control/tulip-control