investigate test_geodtest_geodesic_inverse12 behavior for azi1/azi2/m12

[stonylohr]

This inverse test against GeodTest data currently requires tolerance of 0.02 for azi1 and azi2, and 0.00005 for m12, in order to pass all cases. The azimuth tolerance values in particular are larger than I would expect to be required, and the m12 value is large enough to at least give a quick look.

This is a lower priority than some of the more clear-cut test failures.