Auto-resolve addresses in socket methods

[njsmith]

Currently, one of the awkward differences between socket and trio.socket – really the last awkward difference as of v0.2.0 – is that with socket, you can pass hostnames directly to socket methods, like sock.bind(("localhost", 0)) or sock.connect(("python.org", 443)). In Trio these methods currently require numeric addresses, and there are the extra methods resolve_local_address and resolve_remote_address that do the resolution for you.

This was always a little weird, and really the only compelling reason was because bind as synchronous. But it turns out that bind should be async after all (#241). So we might as well get rid of this last piece of weirdness.

Plan:

• Make bind, connect, etc. all call resolve_local_address/resolve_remote_address automatically as needed
• Deprecate resolve_local_address/resolve_remote_address