consolidate github.com/whyrusleeping/multiaddr-filter into this repo

[marten-seemann]

Part of the effort to reduce repo sprawl.

[marten-seemann]

Now that we have ipcidr support (thanks @MarcoPolo!), it should be trivial to just use that, see libp2p/go-libp2p#1606 for example. No need to merge any more code here.