10-2012
The geolocation routines in wgrib2 are going to be changed.  The problems are 

   (1) internal routines are for a spherical earth
   (2) the IPOLATES library is for a spherical earth and the interface is
       grib1-centric.  Angles are only to milli-degrees.
   (3) many grids are unsupported.
   (4) staggering is unsupported.
   (5) non-spherical (i,j) -> (lat,lon) routines are slow

   (1) can been solved by using the gctpc or proj4 libraries. (done)
   (2) interpolation is to do
   (3) may be helped by proj4
   (4) staggering is to do
   (5) slow geolocation routines (use OpenMP, done), modify libraries (?)

09-2018:
   support for 3 geolocation libraries: internal, gctpc, Proj4
   (1) addressed by gctpc and Proj4, gctpc is the 1st on search order for many years
   (2) IP2LIB_d: supports micro-degrees but still spherical (next release)
   (3) more grid supported but many are unsupported
   (4) staggering is in WMO standard, some grids support WMO staggering
   (5) OpenMP on gctpc which does non-spherical Earth

  On the TO-DO list are
   (1) support FV3 cubed sphere grid
   (2) support FV3 regional grid
   (3) suppoort more grids
   (4) support grids upto 4GB points
   (5) support interpolation for non-spherical Earth