test image permission
Correct behaviour of origin in imshow. Fixes #359.
Prevent image interpolation outside original domain. Fixes #358.
Added test for a regional image on a different projection.
Merge pull request #370 from ajdawson/imshow-bugfixes

Re-projecting non-global images and the origin keyword.
Reduced threshold for Stereographic projection.
Merge pull request #371 from ajdawson/stereographic-extent

Reduced threshold for Stereographic projection.
Correct wrapping and clipping of pcolormesh with IGH. Fixes #319.
Merge pull request #372 from ajdawson/igh-pcolormesh

Correct wrapping and clipping of pcolormesh with IGH. Fixes #319.
Improved testing of LambertConformal and Mercator.
Merge pull request #356 from pelson/remove_some_tests

Improved testing of LambertConformal and Mercator.
pep8 fix
Merge pull request #362 from marqh/testingImages

Test image permission.
Updated handling of 'global' to support v1.3
Made use of the hold_datalim context manager in stock_img.
Fixed use of dataLim and viewLim for global images.
BUG: Broken cartopy img_transform masks
Merge pull request #373 from cpelley/broken_mask

BUG: Fix broken cartopy img_transform masking.
Review actions to remove stock_img behaviour change.
DOC: Updated matplotlib examples with vector plots.

Also updated whatsnew with reference to these enhancements.