spot: Abstract cnf writing in SAT-based minimisation
* spot/misc/satsolver.hh: Declare all functions needed. * spot/misc/satsolver.cc: Implement them. * spot/twaalgos/dtbasat.cc: Abstract writing. * spot/twaalgos/dtwasat.cc: Abstract writing.
* spot/misc/satsolver.hh: Declare all functions needed. * spot/misc/satsolver.cc: Implement them. * spot/twaalgos/dtbasat.cc: Abstract writing. * spot/twaalgos/dtwasat.cc: Abstract writing.