Only test files that rely on extensions compatible with our compiler. The extensions are defined in Test.java
Added check that arrayassignment index is int
fixed regex in extension check
Fixed some inheritence-based typechecking. Refactored to reduce typecheck code duplication
TypeCheckVisitor visits varDecl to check for references to unexisting types
Fixed a bug where reuse of function param name was not detected
Fixed bug where you could extend nonexistent class
Typecheckvisitor now checks arglist for unexistent types