Move GhcModError to Types.hs
Make GhcModT's MonadState instance pass through

..to the underlying monad
Make `parseCabalFile` use MonadError
Generate cabal.sandbox.config in test/data/broken-cabal
Add a test for gmsGet/Put
note
Fix ghc<=7.6
Use the right MonadIO class
Expose GhcModError
Remove GMECabal, GMEGhc constructors from GhcModError for now
Add version number to symbol table cache filename
docs for `ghcModExecutable`
Merge pull request #314 from DanielG/dev

Make GhcModT's MonadState instance pass through and other release-prep