message: refuse iovecs unless a connection set the hello flag
define max cmd size in internal.h
update TODO
test: pass KDBUS_CMD_HELLO_ACCEPT_FD and KDBUS_CMD_HELLO_ACCEPT_MMAP
names: pass back name entries' flags in listing
names: allow registrations for other connection
names: drop unused parameter from kdbus_name_lookup
kdbus.h: fix naming of items in struct kdbus_cmd_name_info_item

in order to make the items iteratable.
names: implement some of the query logic
message: move audit and seclabel gathering to connection

We also need that information from the names database, so let's get it
at the time a client connects and store it along in kdbus_conn.
names: implement more name_query logic

this is totally untested, so beware.
type all internal sizes to size_t
tweak TODO
names: cleanup and document kdbus_cmd_name_query a bit
update TODO
names: kill bogus assignment
names: fix seclable item type
policy: fix reverse cache entry insertion
kill KDBUS_MSG_ID_CHANGE

That flag was originally intended for connections that change their
flags during runtime. We don't allow this anymore (a connection may only
once say HELLO), so we can kill the flag and corresponding match types
alltogether.
test/kdbus-util.c: add support for multi-string payloads