Fix the precipitation and evaporation case statements to use either the...

Fix the precipitation and evaporation case statements to use either the original prate and pevpr (the latter is probably wrong since its units are W/m^{2} whereas FVCOM wants m/s) or P_E or Et (which are probably better choices). Also improve the help at the beginning by adding required fields in Mobj and adding an example usage section

fvcom_prepro/write_FVCOM_forcing.m

 function write_FVCOM_forcing(Mobj, fileprefix, data, infos, fver)
 % Write data out to FVCOM NetCDF forcing file.
 %
-% write_FVCOM_forcing(fvcom_forcing_file, data, infos, fver)
+% write_FVCOM_forcing(Mobj, fvcom_forcing_file, data, infos, fver)
 %
 % DESCRIPTION:
 %   Takes the given interpolated data (e.g. from grid2fvcom) and writes out
 %   to a NetCDF file.
 %
 % INPUT:
-%   Mobj - MATLAB mesh object
+%   Mobj - MATLAB mesh object containing fields:
+%       tri - triangulation table for the unstructured grid
+%       nVerts - number of grid vertices (nodes)
+%       nElems - number of grid elements
+%       nativeCoords - model coordinate type ('cartesian' or 'spherical')
+%       x, y or lon, lat - node positions (depending on nativeCoords value)
 %   fileprefix - Output NetCDF file prefix (plus path) will be
 %       fileprefix_{wnd,hfx,evap}.nc if fver is '3.1.0', otherwise output
 %       files will be fileprefix_wnd.nc.
@@ -48,6 +53,11 @@ function write_FVCOM_forcing(Mobj, fileprefix, data, infos, fver)
 % OUTPUT:
 %   FVCOM wind speed forcing NetCDF file(s)
 %
+% EXAMPLE USAGE:
+%   windBase = '/path/to/output/casename_wnd.nc';
+%   write_FVCOM_forcing(Mobj, windBase, data, ...
+%       'FVCOM atmospheric forcing data', '3.1.6');
+%
 % Author(s):
 %   Pierre Cazenave (Plymouth Marine Laboratory)
 %   Karen Thurston (National Oceanography Centre, Liverpool)
@@ -66,6 +76,8 @@ function write_FVCOM_forcing(Mobj, fileprefix, data, infos, fver)
 %   evaporation in Et). The data in Et are calcaulated from lhtfl whereas
 %   pevpr comes directly from NCEP and to me it seems more sensible to use
 %   that to maintain consistency.
+%   2013-05-14 - Add example usage to the help and specify which fields are
+%   required in Mobj.
 %
 % KJT Revision history:
 %   2013-01-16 - Added support for output of sea level pressure.
@@ -258,7 +270,7 @@ for i=1:length(suffixes)
                     used_dims = [used_dims, 'nNodes'];
                 end
 
-            case 'pevpr'
+            case {'pevpr', 'Et'}
                 if strcmpi(suffixes{i}, '_evap') || ~multi_out
                     % Evaporation
                     pevpr_varid=netcdf.defVar(nc,'evap','NC_FLOAT',[node_dimid, time_dimid]);
@@ -274,7 +286,7 @@ for i=1:length(suffixes)
                     used_dims = [used_dims, 'nNodes'];
                 end
 
-            case 'prate'
+            case {'prate', 'P_E'}
                 if strcmpi(suffixes{i}, '_evap') || ~multi_out
                     % Precipitation
                     prate_varid=netcdf.defVar(nc,'precip','NC_FLOAT',[node_dimid, time_dimid]);