fix in sortcheck_app
Merge pull request #10 from nikivazou/sortcheck_app

fix in sortcheck_app: Niki -- can you add your above comment and my follow up into the .ml file as a (* ... *). This way,
we will have a record when we try to properly implement unification!
misc parser tweaks
allow unification of two different numeric sorts
Merge pull request #11 from nikivazou/numeric

allow unification of two different numeric sorts. 
RJ: Nice, thanks!