fixed issue #43
Updated online REPL URL to frege-lang domain
Introduce Apply and Bind typeclasses
Introduce Alt, Plus and MonadAlt typeclasses
Merge pull request #46 from Frege/type-class

Introduce Apply, Bind, Alt, Plus and MonadAlt typeclasses
handling of pattern literals through rewriting them as pattern guards
flexibly typed int literals completed.
Merge branch 'master' into literals