Rename SocketAddr to InetAddr

[carllerche]

SocketAddr should be an enum of all possible addresses that can be used for sockets, including unix domain sockets and any other socket flavors. What is currently named SocketAddr is really an InetAddr.

[frewsxcv]

Triage: This sounds very reasonable. I haven't been following the IO reform stuff too closely, but as far as I know, the io::net submodule has yet to be proposed

[steveklabnik]

/cc @aturon

[frewsxcv]

Relevant RFC PR: rust-lang/rfcs#807

[aturon]

Hm, unfortunately this wasn't taken into account with IO reform, and seems to still be an issue. The renaming makes sense to me. Thoughts, @alexcrichton?

[aturon]

Nominating for 1.0-beta P-backcompat-libs.

[alexcrichton]

We may wish to reconsider the socket_addr method names on each of the socket types as well, but this renaming is fine by me.

[pnkfelix]

P-backcompat-libs, 1.0 beta

[carllerche]

I submitted an RFC PR for this change: rust-lang/rfcs#923