Planetary vorticity bug fixes. Closes #5.
Planetary vorticity bug fixes. Closes #5.

Support for computing planetary vorticity for Gaussian grids was
omitted. This is now fixed. Planetary vorticity for offset grids
remained broken after commit 5a70842352cea42eeee2163abce492b4501d4614
so this is also fixed.

nicolasfauchereau/windspharm,ajdawson/windspharm