Added grammer rules and classes for Bool and Str
Fixed grammer mistakes and generated new parser
Forgot to add files
Added generics to Expr types
Revert "Added generics to Expr types"

This reverts commit 4a71ebd3e8f2e1abe75fb6029b173bd5f989977d.
Re-added antlr library
Pulled some more superclasses up.
Made some more refactorings
Worked further on questions and conditionals
Implemented computation, now for some more unit tests.
Form is now the starting symbol of the language. Created helper functions in TestParser superclass for easily testing forms, statements and expressions.
Refactored some more
Splitted out and added some more unit tests
Finally got around to committing the first part of the type checking visitor mechanism as well as some refactorings after the motherboard of my laptop broke :(
Now validates if a binary expression's left hand side and right hand side are reduceable to the types they can be, both for expressions that can hold one type (Add for example) as one that can hold several (EqualTo and NotEqualTo).
Visitor can now also check UnaryOperations. Also refactored some more.
Added type checking for conditions in a conditional.
Made some more refactorings, removed some unnecessary super classes in preparation of identifier type checking. Also added a test which assures the grammer is not affected by the dangling else problem.
Made some more refactorings, renamed Primary to Datatype and made it the superclass of only Str, Int and Bool. Also doesn't extend from QLExpression anymore.
Whoops, forgot the assertion.