This extends the experimental incremental JSON API to allow arbitrary
smtlib subexpressions, defining smtlib constants and to allow access of
signals by their .yw path.
It also fixes a bug during .yw writing where values would be re-emitted
in later cycles if they have no newer defined value and a potential
crash when using --track-assumes.
The --track-assumes option makes smtbmc keep track of which assumptions
were used by the solver when reaching an unsat case and to output that
set of assumptions. This is particularly useful to debug PREUNSAT
failures.
The --minimize-assumes option can be used in addition to --track-assumes
which will cause smtbmc to spend additional solving effort to produce a
minimal set of assumptions that are sufficient to cause the unsat
result.
Jannis Harder