minor changes
added TupleExprs and support to the AST
minor error fixes caused from adding TupleExprs
finished fixing up annoying type errors from adding TupleExprs and TupleType to the AST/grammar
minor bug fixes, WIP
fixed TypeChecker for new TupleTypes, simplified the type checker.
updated typechecker to handle node argument checking to create exquisite error messages
generalized node inlining