store DPIDs from file in correct struct index

- Directivity Pattern ids read from file are now stored in the correct index instead of overritting index 0.
- print informative error message when Directivity Pattern ID (DPID(s)) specified is/are not found.
- Repeat last DPID value for remaining objects if not all objects' DPID are specified when -DPID commandline flag is used. e.g if -DPID 0 1 is equivalent to -DPID 0 1 1 1 .