tests: Added some XYZ tests
tests: Added some XYZ tests

Added tests for Geom_iter on a file, and Angle_iter & Dihed_iter
  on the direct data.

Also added #TEST: annotations for tests needed to be added, and
  pulled the `self.longMessage = True` assignment into the `SetUp`
  method for `TestOPANXYZGoodFileData`

bskinn/opan,bskinn/opan