Expose phase/unphase in the C API

[sfiruch]

It would be useful to have the phase and unphase functions exposed in the C interface:

void ccadical_phase (CCaDiCaL *wrapper, int lit) {
  ((Wrapper *) wrapper)->solver->phase (lit);
}

void ccadical_unphase (CCaDiCaL *wrapper, int lit) {
  ((Wrapper *) wrapper)->solver->unphase (lit);
}

[Dekker1]

In general I think it would make it much easier for other languages to connect if the features from the IPASIR-UP interface were available from C. I might be able to commit some time to writing this C-interface, if there is interest from the maintainers.

[arminbiere]

Thanks, nice enhancement proposal. Regarding IPASIR-UP, please hold your breath. IPASIR-UP is not completely stable yet. We have some additional insights and are working on it. Of course if this gets more stable we will also add a C interface.