fix/interpolator_tol

This fixes a bug in the interpolator which is constantly causing buildbot to fail.

The issue is basically a conflict between a tolerance chosen at l352 libary/fieldutils/interpolator.cpp and one at l124 libary/stdregions/stdexpansion2d.cpp. The tolerance in a finding operation was set to be the same as a tolerance in physevaluate, this meant that there is a fringe case where these two compare exactly causing the assert. Really the first tolerance should be lower than the second to ensure the process goes through.