Verify API mapping by comparing function output with several inputs.

Dropped `eqpy.math.fmod`, because it may vary according to platform.
Add `math.expm1` to test exemption; better test output.
python3 compatible print function; add 'erf' and 'erfc' to math skip
skip 'gamma' and 'lgamma' for tests in math
Change 'atan2' domain to be nonzero
Merge pull request #1 from eriknw/test_domains

Test domains