fix bug occurring when roi is defined in several ways in config.json
fix bug occurring when roi is defined in several ways in config.json

When the input json config file contains several definitions of the
region of interest (roi), e.g. image coordinates and utm coordinates,
the definitions overwrite each other with this order of precedence
(highest priority first):
- full_img (boolean flag)
- roi (x, y, w, h image coordinates)
- roi_utm (x, y, w, h utm coordinates)
- roi_kml (path to kml file)
- prv (path to a preview file for graphical selection)

jmichel-otb/s2p,dyoussef/s2p,dyoussef/s2p,carlodef/s2p,carlodef/s2p,jmichel-otb/s2p,MISS3D/s2p,dyoussef/s2p,dyoussef/s2p,MISS3D/s2p,mnhrdt/s2p,mnhrdt/s2p,MISS3D/s2p,jmichel-otb/s2p,MISS3D/s2p,jmichel-otb/s2p