@travissluka Merged your commits and passed all tests.
It initially failed to interpolate Geometry's gmask as sea_area_fraction to observation locations because of data type (int to double not workable), I created a new Geometry field "ggmask" of double type to interpolate as a temporary solution. May improve it later.
I made several tests for this passing vector of pointers (to Field) from C to Fortran. Hopefully it'll work ok.
@travissluka Merged your commits and passed all tests.
Close #54 .