todo:
* Unicast responses/queries
* Legacy unicast

* add SRV and TXT records referenced from PTR records automatically to packet
* add A and AAAA records referenced from SRV records automatically to packet

* Add some APIs to get the clean service name from RR for browsing

* release!

done:
* Probing/Conflict resolution
* uniqueness
* respect escaping in name serialization
* really send goodbye packets
* refresh subscribed records only
* FLX_DNS_TYPE_ANY support
* Known-Answer suppression client part
* Known-Answer suppression server part
* make flx_server_add_text() and flx_server_add_service() variadic functions
* name compression
* remove expression "rrset" from source files
* defend our entries on incoming goodbye
* allow NULL bytes in TXT records
* add flx_server_add_service_strlst() and friends
* change flx_* to avahi_*