added rewrite rules

Alternatively, we could have just passed the rewrite rules to Z3, but
this sounds like it would be more unpredictable and possibly much
slower. Could be worth a try though.
Merge branch 'alt-abd' of github.com:seplogic/corestar into alt-abd

gah, I misgited
rewrite * to /\ inside quantifiers

and better Syntax.on_quantifier