Add a 'replace-screenshots' command to appstream-util
Add a 'replace-screenshots' command to appstream-util

This is designed for distros to use in spec files to replace the upstream
screenshots with something distro-specific, more suitable, or less offensive...

ikeydoherty/appstream-glib,hughsie/appstream-glib,ikeydoherty/appstream-glib,kalev/appstream-glib,superm1/appstream-glib,ximion/appstream-glib,superm1/appstream-glib,hughsie/appstream-glib,ximion/appstream-glib,mitya57/appstream-glib,hughsie/appstream-glib,kalev/appstream-glib,ximion/appstream-glib,mitya57/appstream-glib