Added bindings of fmod() in python

[mcrescas]

This pull request exposes to both array and tensor types the function fmod(...) in Python.

[wjakob]

It seems relatively complicated to implement fmod this way. Can you not use the same approach as in array_router.h?

[wjakob]

[wjakob]

(ping, is this still relevant?)

[Speierers]

I am closing this PR as we removed bindings for those fancy multiply-add operations, hence we are not going to add this one.