Enhancement: WRF Coupled CMake Build and Documentation

[scrasmussen]

TYPE: enhancement

KEYWORDS: WRF, CMake

SOURCE: Soren Rasmussen, NSF NCAR

DESCRIPTION OF CHANGES: Current documentation and CMake build work only for WRF + WRF-Hydro coupled mode using the older compilation method. CMake build and documentation updated to now have a functioning coupled build. The CMake instructions were adapted from WRF's CMakeLists.txt files.

TESTS CONDUCTED: Moved WRF-Hydro's src/ directory to WRF/hydro and built with CMake. Used the following command with GNU modules

$ ./configure_new -x -p gfortran/gcc -- -DWRF_CORE=ARW -DWRF_NESTING=BASIC -DENABLE_HYDRO=ON \
    -DWRF_CASE=EM_REAL
$ ./compile_new -j 4

[rcabell]

LGTM. We should probably think about a quick GitHub test for the coupled build, if even just that it compiles without error.