Overload Variant For Modulus Assignment

This pull request fully resolves #901 completely and overloads the variant type for the modulus assignment operator. It also fixes a secondary parsing error where the modulo operator was completely missing.

@sorlok Would you like to pull and test these changes to see if they fix any bugs in any of your projects and to make sure they don't break anything? I've done some pretty extensive regression testing over here as I usually do, the usual Project Mario, FPS tutorial tests and such. #901 has a simple test case if you have nothing else to test.