Merge pull request #352 from pelson/katrina_lambert

Updated the Hurricane Katrina example to use Lambert Conformal.
Merge pull request #353 from pelson/summarise_package

Caught modules which are not importable. This came from applying the sum...
Regridding in projection space for vector plots.
Refined projection space regridding.
Merge pull request #366 from ajdawson/vector-transform-regrid

Regridding in projection space for vector plots.
Improved testing of LambertConformal and Mercator.