[G12] minuit MNEXCM return code meanings

[Craig Bookwalter]

Yesterday I was complaining about never knowing what the heck the return 
values from MIGRAD mean--well, what I was looking at was actually a 
return code for MNEXCM, not MIGRAD itself. But here are the codes and 
their meanings in case anyone else is interested (from the ROOT TMinuit 
documentation):

    = 0: command executed normally
      1: command is blank, ignored
      2: command line unreadable, ignored
      3: unknown command, ignored
      4: abnormal termination (e.g., MIGRAD not converged)
      5: command is a request to read PARAMETER definitions
      6: 'SET INPUT' command
      7: 'SET TITLE' command
      8: 'SET COVAR' command
      9: reserved
     10: END command
     11: EXIT or STOP command
     12: RETURN command


--cb