Make the LocalCompiler more local

- thread switch argument through compilation

- interpret Test on Switch at compile time

- this means that a flow table is only for one switch

Slower, but simpler. And correct-ier.

- Also fixed up front-end and unit test code in light of this change.
Merge pull request #163 from frenetic-lang/nate-marco-bugfix-ii

Make the LocalCompiler more local