Allow the engine to be NULL in PeasExtensionSet
Allow the engine to be NULL in PeasExtensionSet

gregier/libpeas,GNOME/libpeas,gregier/libpeas,chergert/libpeas,GNOME/libpeas,gregier/libpeas,chergert/libpeas,chergert/libpeas,Distrotech/libpeas,Distrotech/libpeas,Distrotech/libpeas,gregier/libpeas