Routines for setting up NERSC nesting in hycom 2.2

nestport : Sets up a ports.input file which can be understood by 
           standard hycom nesting routines. It only treats ports
           along boundaries of the model grid. If the 2nd grid cell from the
           boundary is ocean, a port can be placed there. Requires grid/depth
           files to be present in running directory.

nestini  : Sets up nesting relaxation mask which can be understood 
           by standard hycom. Again, only treats points along boundary.
           If the 2nd grid cell from the boundary is ocean, a port can be
           placed there.  Requires grid/depth files to be present in running directory.


checknest: Diagnostic routine to analyze nesting files dumped by NERSC
           hycom

nestpivot: used to prepare a outer model for nesting to an inner model.
           It sets up pivot points and interpolation details for the 
           outer model. (which it needs when dumping nesting files).

TODO: Make sure nestini calculates boundary distance better 
      (see nestbat 2.2)