Loosen threshold on test of parametric coordinates

The UnitTestParametricCoordinates test uses a pseudorandom number generator to create some random set of parametric coordinates, convert to world coordinates, and then back to parametric coordinates.

This has been working fine except that the world coordinate to parametric coordinate conversion is not extremely precise for some cell shapes. (It would not be cost effective to make it more precise.) Because of this, the test_equal for this comparison has a pretty high threshold.

While looking at a dashboard I happened across a failure for this test. It turns out that one of the parametric coordinates created for the pyramid test for seed 1465529014 was just outside of this threshold, but otherwise correct. I raised the threshold a little to try to prevent this error.