Defined the built-in module the "File" data type. I would like to add a module builder, a kind of editor for constructing mini-Dao programs, but I am not quite sure where to begin. I will need to think about it some more.  Also, changed the IF and IFNOT constructors to WHEN and UNLESS (respectively), and added a new IF and IFNOT constructors to the 'RWEval' and 'XEval' data types.