The array creation functions have the most to gain:
1. np.asarray is 4 times faster and commonly used.
2. Other functions are wrapped using __array_function__ in Python
making it more difficult
This commit (unfortunatly) has to do a few things:
* Modify __array_function__ C-side dispatching to accomodate
the fastcall argument convention.
* Move asarray, etc. to C after removing all "fast paths" from
np.array (simplifying the code)
* Fixup imports, since asarray was imported directly in a few places
* Replace some places where `np.array` was probably used for speed
instead of np.asarray or similar. (or by accident in 1 or 2 places)