Adds many long double variants (e.g. expl) that were previously omitted.
No functions have been removed.

I've omitted the identifier for trivial parameters in new functions.
However, I've retained them for existing functions for compatibility
with legacy kwargs.

Classes of functions/macros that are still missing:
 - error-handling ones, like math_errhandling and MATH_ERRNO
 - Bessel functions like j0, y0

Fixes cython/cython#3570