Better code in Language.
StFunctionCall to StProcedureCall.
type Used = Init = Pure = Bool
Added 'pure' attribute to SymInfo.
Deleted Access.hs.
checkExpression now returns (DataType, Pure), instead of DataType,
now we check that an initialization of array size is done only by literal integers,
"thighter" code in Checker.hs,
fixed a bug where it would state a Struct was 'defined but not used' even after using it.