Corrected reading of spatially varying bottom friction variables

[arango]

Corrected a problem in get_grid.F when reading any of the spatially varying bottom friction variables (rdag, rdrag2, or ZoBot). We cannot have string variables in the CASE argument list:

          CASE (TRIM(Vname(1,idZoBL)))
            ...
          CASE (TRIM(Vname(1,idragL)))
            ...
          CASE (TRIM(Vname(1,idragQ)))
            ...

These statements are illegal in F90/F95. If string variables are used, we need to defined and initialized them with a PARAMETER clause. That is, they need to be constants. Alternatively, it can be replaced with literal strings:

          CASE ('ZoBot')
            ...
          CASE ('drag')
            ...
          CASE ('drag2')
            ...

However, this will not allow the user to provide different names in varinfo.dat.

The solution is to read these variables outside the SELECT CASE statement and still allow alternative NetCDF variables names with customized metadata.

Many thanks to Kate for reporting this problem.