ENH: Vectorize float min/max operation with sse2

Improves performance by ~1.5/3.0 for float/double.
ENH: vectorize base math with SSE2

Improves performance by ~1.5/3.0 for float/double for inplace or cpu
cached operations
MAINT: guard prototypes with HAVE_EMMINTRIN_H

avoids declared but not defined warnings
MAINT: fix an uninitialized use in the no fenv fallback
DOC: use full ufunc names
Merge pull request #3419 from juliantaylor/vectorize-rest

min/max and base math vectorization