Usage of prio_circ2dlp is  as follows:

    prio_circ2dlp <file> <min_atoms:different:priorities:separated> 
                  [-v <varying> -f <fixed>] 


Different priority classes are separared with colons. Notice that 
prio_circ2dlp assumes programs circ2dlp and lpcat to be found at 
the same directory. Prio_circ2dlp writes on temporary files 
prio_circ2dlp_output_file and prio_circ2dlp_tmp_file