Improved TypeChecker Error Handling - now makes code suggestions, and checks entire file instead of stopping on first error.
Bug fixes for type checker error handling, tidied up error test files.
Final debugging for typechecking error handling, tidied up some error messages and added test file for typechecker error messages and recovery.
Debugged issues with some errors being reported multiple times, and with undeclared variables not being properly handled. Added test for both cases.
Merge pull request #18 from DanielJCampbell/master

Improved typechecker error handling significantly.