grid.xml: Bug fixes for projections that use PositiveWest or Planetographic...

grid.xml: Bug fixes for projections that use PositiveWest or Planetographic coordinate systems. The BASELAT and BASELON parameters are now expected to be in the units of the projection (if your cube has a planetographic latitude system, and baselat=50, then there will be a line at the planetographic latitude of 50). 
GroundGrid.h: 2011-01-25 Steven Lambright Now uses native unitsto the projection, Lat/Lon classes, and several bug fixes when it comes to out of range values or non-standard projection types. 

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@1614 41f8697f-d340-4b68-9986-7bafba869bb8