float64 reg coord if needed

restored pp_netcdf tests

test revert

test refactor

comment tidy
Merge pull request #928 from marqh/hires_reg_coord

float64 reg coord if needed
ENH: Stash code to field code translation table.
MAINT: Existing functionality maintained.

All tests will pass ensuring that current functionality is
maintained.
MAINT: Added unittests for the added functionality.
BUG: Corrected the replaced table.
MINT: Changes based on review.