Low Level

IReactorTCP.connectTCP will be extended with these (backwards compatible) changes:

1. An IPv6 address literal, optionally(?) with a percent-embedded scopeid will be allowed as the value of the host parameter
2. The bindAddress parameter will accept 4-tuples. The first element is an address like the above, the other three are port number, flow info, and scope id.
   1. (Maybe bindAddress values shouldn't be tuples but should be nice structured objects instead)
3. If host is IPv6, bindAddress must be as well, and vice versa.

IReactorTCP.listenTCP will be extended with these (backwards compatible) changes:

1. interface will accept an ipv6 address literal value like the one described above
2. The default listen address will still be INADDR_ANY (this is a non-change; pass "::" if you want IPv6 servers, or see the high level APIs)

IReactorUDP.listenUDP will be extended in an analogous way to IReactorTCP.listenTCP

IUDPTransport.write will