[Mpi3-tools] MPIT_CTRLVAR_WRITE return codes

Hi all, in the current draft, MPIT_CTRLVAR_WRITE can return the error codes PIT_ERR_SETNOTNOW and PIT_ERR_SETNEVER only. For my implementation it would be useful, if you could return something indicating that the value you want to write is out of range or that not all elements could be changed (if a control variable contains more than one element). Andreas