added helper methods to simplify test cases
Typechecker added (includes symbol table)
added testcases for typechecker
refactored AST nodes into different packages
renamed ASTNodeVisitor to Visitor
Added typeOf and isCompatible methods
made the Visitor generic
Added semantic validation
Implemented TypeChecker, refactored ASTPrinter and added testcases.
type fix and polish
Merge branch 'master' of github.com:software-engineering-amsterdam/sea-of-ql
Reverted from d9b5ac38d8bfb4c9d1876b2f923b66d1bd16e315
removed bugs from typechecker
refactored TypeChecker and TypeCheckerVisitor into one class
created typed ErrorList
Merge branch 'master' of https://github.com/software-engineering-amsterdam/sea-of-ql
Env now checks parent envs of existence of Ident
Added block element to better handle form body and ifthenelse's
Added if then else. Updated type checker
Identation
Removed lib files