Fix ChangeLog date.
Consolidate conditionals in mp sin/cos functions

Consolidate conditionals in multiple precision sin and cos functions
to prepare the code for addition of probe points.
New inputs for exp

A more comprehensive set of inputs for exp, including all slow paths.
The inputs have been shuffled so that they don't give a false-positive
due to a hot cache.
Benchmark inputs for pow

These inputs cover all normal processing paths for pow including all
its slow paths.