Added a new built-in function "call()", which takes a callable object as
the first parameter, and a list of arguments as the second parameter,
and calls the function object with the list of arguments.
Bug fix: this was a bug that was really difficult to track down, the "delete()" function stopped
working because the 'ExecUnit' being updated but the updates were being lost. A full explanation of
the fix is written as comments in the source code which are included in the diff of this commit.
Bug fix: forgot to rewrite the 'Dao.Interpreter._updateLocal' function to make use of the
'Dao.Interpreer.execUnitUpdateRef' function. It was still using
'Dao.Interpreter.innerDataUpdateIndex', which was failing to define any local variables. This has
been fixed.