Add a check for the --logo option to ensure weblogo program is present
Add a check for the --logo option to ensure weblogo program is present

The availability of the weblogo programm is now checked when the --logo option is set.
It adds a custom action for argparse and relies on the subprocess library

jbarnoud/PBxplore,pierrepo/PBxplore,pierrepo/PBxplore,jbarnoud/PBxplore,HubLot/PBxplore,HubLot/PBxplore