handle "max_relevant" uniformly

honor the default max relevant facts setting from the SMT solvers in Sledgehammer

have SMT solvers report the number of facts that they should have by default in Sledgehammer -- the information might not seem to belong there but it also belongs nowhere else, for how is Sledgehammer to know how different solvers deal with hundreds of facts?

return all facts for CVC3 and Yices, since there is no proof parsing / unsat core extraction