* test/data/valid-messages/opposite-endian.message: fix test
	to use proper type for rply field

        * test/data/invalid-messages: add tests for below validation

	* dbus/dbus-message.c (decode_header_data): validate field types,
	and validate that named fields are valid names
	(decode_name_field): consider messages in the
	org.freedesktop.Local. namespace to be invalid.

	* dbus/dbus-string.c (_dbus_string_validate_name): new