Prerequisites:
- NetCDF is required by MAPL, so your ESMF build should include it
- The command "gmake" must be available.  If your distirbution is called "make", add a symlink from gmake to make.  

Build instructions:

1. Set the ESMF environment variables, build and install ESMF.  Keep them set for the MAPL compilation, especially ESMF_DIR, ESMF_COMPILER, and the ESMF_NETCDF_* variables. ESMF_DIR is the root directory of the ESMF source tree. ESMF_COMPILER is the compiler suite used to compile ESMF.  The ESMF_NETCDF_* variables point to the include and library directories for the third party NetCDF library.

2. Set the ESMFMKFILE environment variable.  Typically ESMFMKFILE points to esmf.mk file set up in step 1. more information about this variable can be found here: http://www.earthsystemmodeling.org/esmf_releases/public/last/ESMF_usrdoc/node7.html. 

3. In MAPL directory, make install && make esma_doc
