Input parameter for buffer size

 - Old default value of NetCDF buffer (512 time steps) could easily lead
   to huge memory requirements (>>10GB per node) for periods ~5s
 - Old solution was to change this value in source code in
   nc_routines.F90
 - Introduced input value NETCDF_DUMP_BUFFER into inparam_advanced to
   set this value the proper way.
 - Changed inparam_advanced.TEMPLATE accordingly
Merge branch 'buffersize_param'