names: add the activator connection itself to the list of of activator names
names: fix condition for activator listing
kdbus.h: document ENOENT error
names: rework list logic once more

now, KDBUS_NAME_LIST_ACTIVATORS will list name entries regardless
whether they have been activated or not.
names: fix 'added' assignment
names: cosmetics
do not filter directed messages sent to monitor connections
TODO: update
rename "id" to "owner_id" for all actions on behalf of other connections
connection: do not guess-check for target connection without ref'ing it
policy: remove inline declaration, it's the compiler's decision
match: check for currently owned names
allow HELLO to impersonate somebody else
metadata: re-initialize meta object, we might re-use it
metadata: use append_data for credentials
connection: move messages addressed to a name back to the activator
metadata: always allocate and don't embed meta object
handle: do not put "ep" and "conn" in a union
do not deny writing messages to an activator connection
return error in kdbus_name_release()