Checking for NAN
Checking for NAN

The ASSERT_DBL_NEAR_* macros failed to test properly for NAN cases.
This commit remedies that and brings in two new macros: ASSERT_NAN
and ASSERT_NOT_NAN.

ELIFE-ASU/Inform,dglmoore/Inform,ELIFE-ASU/Inform,dglmoore/Inform