Merge pull request #8 from jdegoes/master

add instances for either, maybe, and tuple, and some helper functions
not working
workaround for type inference???
massive cleanup & fixing of bugs / indeterminism
more cleanup
more cleanup
added more combinators
update to newly released free
code cleanup, bug fixing
further code cleanup
more bug fixes
bug fixes
bug fixes
Merge branch 'master' of github.com:purescript/purescript-quickcheck