This will raise the ```TagExcess``` exception only after running all the scenarios. The current version of cucumber raises the exception before running any scenarios which I think is the desired behavior?

Since parsing, compilation, and execution are part of the same chain, replicating the existing behavior seems a bit complex at least to a cucumber codebase n00b. Also possible I'm completely missing something.

When I was looking into it I contemplated an extra parsing pass outside of core but that seemed a bit gnarly.