Lots of bugfixes.
Enabled var_par_access
Fixed code for handling overwrites of files (the mode was read from old file).
Define mode is needed for NetCDF4-classic files, bugfix.
Added retrieval of number of groups for a file. Also added this
to print-out statement.
Added rename_var to the code.
When creating a variable the user can now also set the var_par_access (to ease the code for the user. It will only be set if the file allows, i.e. nc4).
Fixed test for ncdf, now fully works.