don't pass too many facts on the first iteration of the SMT solver

catch TimeOut exception

ensure the SMT solver respects the timeout -- Mirabelle revealed cases where "smt_filter" apparently never returns

if SMT used as a filter in a loop fails at each iteration, returns the first error, not the last, since it is more informative -- the first error typically says "out of memory", whereas the last might well be "the SMT problem is unprovable", which should be no surprise if too many facts were removed

removed explicit "Interrupt" handling for conformity with async model -- unfortunately the user loses the information about how many scopes were checked, but this needs to be retought with the new interface anyway

make Nitpick datatype tests faster to make timeout less likely

invoke SMT solver in a loop, with fewer and fewer facts, in case of error