ENH: NearlyEqual fuzzy comparator and SafeDivision

Added a "NearlyEqual" fuzzy comparator based on Knuth,
"The Art of Computer Programming (vol II)" and safe division
that catches overflow/underflow.

Change-Id: Iec61417c59936831a44f8961eeaa7d44c40bee64
ENH: Use NearlyEqual fuzzy comparator

Change-Id: If31eaf35bae764e7c72a98e8ef726adba0c5764f
WIP: attempting to fix test

Change-Id: I6826aa06799843abde41267c77e4f40951403716