TpPresenceMixin: enforce the "may set on self" flag
TpPresenceMixin: enforce the "may set on self" flag

Also explicitly check for OFFLINE, UNKNOWN or ERROR, and don't allow
those to be set on yourself, whatever the CM might say to the
contrary.

Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib,Distrotech/telepathy-glib