Refactor and deprecate

[Stebalien]

Looking at this package:

1. It's only used from go-libp2p-swarm.
2. Much of it's functionality belongs in either swarm or go-multiaddr-net (where it will be more discoverable).

In an effort to slim down our package list a bit, we should copy any functions we need into their respective places and then deprecate (BUT NOT REMOVE) this package.

[Stebalien]

@anacrolix interested?

[anacrolix]

It seems like a good idea. I see https://godoc.org/github.com/libp2p/go-addr-util?importers. We could definitely archive this repo to ensure nothing more gets added.

[anacrolix]

It feels like busy work, unless something in here is wrong, or may mislead users.

[Stebalien]

No, this is super-low priority. I noticed because I was fixing a bug in this library and realized we mostly don't need it.

[Stebalien]

(I just know you're interested in reducing our repo count).

[ghost]

I can take this as part of multiformats/multiaddr#88

[raulk]

Agree with this change. Too much unnecessary indirection at the moment.