Create variable `uniform_lon_lat`

In module `input_ssh_m`. Read it from `input_ssh_nml`.

Inst_eddies/input_ssh.f90

@@ -11,6 +11,9 @@ module input_ssh_m
   ! size of ssh array in input NetCDF, assuming no repeated point if
   ! the grid is global
 
+  logical, protected:: uniform_lon_lat = .true.
+  ! grid is cartesian and uniform in longitude and latitude
+
   private get_var
 
 contains
@@ -53,7 +56,7 @@ contains
     real lon_max, lat_max ! longitude and latitude, in degrees
     integer copy
     namelist /grid_nml/ corner_deg, step_deg, nlon, nlat, periodic
-    namelist /input_ssh_nml/ periodic
+    namelist /input_ssh_nml/ periodic, uniform_lon_lat
 
     !----------------------------------------------------------------------