remove function first
remove function first

`first()` reset the state to an initial value.
Now parse no longer uses global variables this is not needed any more.

josdejong/mathjs,josdejong/mathjs,FSMaxB/mathjs,FSMaxB/mathjs,FSMaxB/mathjs,FSMaxB/mathjs,josdejong/mathjs,josdejong/mathjs,josdejong/mathjs,FSMaxB/mathjs