Major refactoring and reorganization needed.

[DefinitelyNotAGirl]

The code base has become very cluttered and messy.

planned fixes

• rewrite the whole error/warning system, give every type of error/warning its own class
• convert internal errors (such as errorCompilerBug) into exceptions, use a custom class
• declutter parser.cxx, potentially break up the parse function
• remove misc functions from parser.cxx
• change errors inside resolve to throw exceptions rather than returning nullptr

[DefinitelyNotAGirl]

finished by #37