rotated lat-lon using NCEP template (NAM)

[webisu]

v5.1.0 has problems with the NCEP-defined rotated lat lon grids as used by NAM. Was trying
to interpolate from NAM NCEP-defined rotated lat-lon to a 1 degree global lat lon grid. The domain
of the defined grid points was wrong.

[edwardhartnett]

When working on this, we can test against develop branch of ip in the wgrib2 project. So wgrib2 can test out the feature before the ip release.

@webisu we are going to need a test in wgrib2 which demonstrates the problem you outline...

[webisu]

I un-commented the line use_ncep_post_arakawa();
in New_grid.c and things the nam (NCEP def rot lat-lon) and COSMO (WMO def rot lat-lon) worked.

[edwardhartnett]

@webisu we need a unit test that proves this. What is that test going to look like?