Merge pull request #506 from RosettaCommons/rhiju/angle_deriv_tol
updating tolerance on angle_deriv function from 1.0e-3 to 1.0e-8.
This fix does cause changes in several integration tests that carry out minimizes. In several cases, the final energy is noticeably better than before (by many Rosetta units), but in most cases changes to final energies are less than 0.1 Rosetta units.