Wrap transform methods of Robinson projection to avoid passing NaNs.
Merge pull request #277 from pp-mo/robinson_nans

Wrap transform methods of Robinson projection to avoid passing NaNs.
Fixed @rhattersley's lingering figure in test_set_extent.
Merge pull request #269 from cpelley/stop_inf_loop

BUG: capture infinite loops creating LinearRings
Merge pull request #281 from pelson/tidy_up_after_rhattersley

Fixed @rhattersley's lingering figure in test_set_extent.
fix non ccw for countourf
only contourf ccw force
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