added a Buildfile for easy building with buildr, implemented control.alternative and started porting parselib.abstract (as parselib.standard)

Signed-off-by: Pepijn Kokke <pepijn.kokke@gmail.com>
abstract/standard parser combinators now compile, and are instances of their respective frege typeclasses.

Signed-off-by: Pepijn Kokke <pepijn.kokke@gmail.com>