Port over gll-combinators test suite

[djspiewak]

Most of the gll-combinators test suite is highly applicable to parseback, and the syntax is very very close. It should be relatively easy to port over most of the tests. As an initial spike, any test which is failing should just be marked as pendingUntilFixed.

The gll-combinators test suite is here.

[ChristopherDavenport]

Are you opposed to depending on scalacheck and specs2-scalacheck as in the gll-combinators library? Would make implementation simpler.

[djspiewak]

Not at all opposed! Very much in favor, in fact.

[djspiewak]

Started the process of moving things over. Found a bunch of bugs in the process. Still resolving, but work is in master now.