Fix wrong assumption about AF_INET and AF_INET6

darcs-hash:20090224114038-58103-857fa72578c9e76e73fcd1f849d39d2560b8222a
In RTPTransport, check if arguments are IP addresses, not hostnames

darcs-hash:20090224114105-58103-d4a37f1d2b2a0827038f383f6f5997fe1426297f