Break reference cycle between CamelSession and CamelService.
Break reference cycle between CamelSession and CamelService.

CamelService now holds only a weak pointer to CamelSession.

gcampax/evolution-data-server,gcampax/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server,gcampax/evolution-data-server,gcampax/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server