SciTools/cartopy — pull request #263 by bjlittle (2013-04-15 13:39:21+00:00)
Title: OSNI projection.

This PR adds the OS NI projection and corrects the image detection for a target domain and zoom level.

Note that, when creating an image nest from directory sources using ```NestedImageCollection.from_configuration()```, the order of the directory sources is automatically sorted by largest area - thus removing this order requirement from the user.

Module doc-strings have also been added.