Add a 'split-appstream' command to appstream-util
Add a 'split-appstream' command to appstream-util

This allows us to split an AppStream file into AppData or MetaInfo files.

ximion/appstream-glib,ximion/appstream-glib,ikeydoherty/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib,ikeydoherty/appstream-glib,ximion/appstream-glib