The primary change here is to always write() once before adding
	the write watch, which gives us about a 10% performance increase.

	* dbus/dbus-transport-unix.c: a number of modifications to cope
	with removing messages_pending
	(check_write_watch): properly handle
	DBUS_AUTH_STATE_WAITING_FOR_MEMORY; adapt to removal of
	messages_pending stuff
	(check_read_watch): properly handle WAITING_FOR_MEMORY and
	AUTHENTICATED cases
	(unix_handle_watch): after writing, see if the write watch can be
	removed
	(unix_do_iteration): assert that write_watch/read_watch are
	non-NULL rather than testing that they aren't, since they
	aren't allowed to be NULL. check_write_watch() at the end so
	we add the watch if we did not finish writing (e.g. got EAGAIN)

	* dbus/dbus-transport-protected.h: remove messages_pending call,
	since it resulted in too much inefficient watch adding/removing;
	instead we now require that the transport user does an iteration
	after queueing outgoing messages, and after trying the first
	write() we add a write watch if we got EAGAIN or exceeded our
	max bytes to write per iteration setting

	* dbus/dbus-string.c (_dbus_string_validate_signature): add this
	function

	* dbus/dbus-server-unix.c (unix_finalize): the socket name was
	freed and then accessed, valgrind flagged this bug, fix it

	* dbus/dbus-message.c: fix several bugs where HEADER_FIELD_LAST was taken
	as the last valid field plus 1, where really it is equal to the
	last valid field. Corrects some message corruption issues.

	* dbus/dbus-mainloop.c: verbosity changes

	* dbus/dbus-keyring.c (_dbus_keyring_new_homedir): handle OOM
	instead of aborting in one of the test codepaths

	* dbus/dbus-internals.c (_dbus_verbose_real): fix a bug that
	caused not printing the pid ever again if a verbose was missing
	the newline at the end
	(_dbus_header_field_to_string): add HEADER_FIELD_SIGNATURE

	* dbus/dbus-connection.c: verbosity changes;
	(dbus_connection_has_messages_to_send): new function
	(_dbus_connection_message_sent): no longer call transport->messages_pending
	(_dbus_connection_send_preallocated_unlocked): do one iteration to
	try to write() immediately, so we can avoid the write watch. This
	is the core purpose of this patchset
	(_dbus_connection_get_dispatch_status_unlocked): if disconnected,
	dump the outgoing message queue, so nobody will get confused
	trying to send them or thinking stuff is pending to be sent

	* bus/test.c: verbosity changes

	* bus/driver.c: verbosity/assertion changes

	* bus/dispatch.c: a bunch of little tweaks to get it working again
	because this patchset changes when/where you need to block.