Refactor multiaddr crate. (#498)

Refactor multiaddr crate.

- Remove `AddrComponent`. Instead `Protocol` directly contains its
associated data.

- Various smaller changes around conversions to Multiaddr from other
types, e.g. socket addresses.

- Expand tests to include property tests which test encoding/decoding
identity.

core/src/lib.rs

@@ -253,7 +253,7 @@ pub mod transport;
 pub mod upgrade;
 
 pub use self::connection_reuse::ConnectionReuse;
-pub use self::multiaddr::{AddrComponent, Multiaddr};
+pub use self::multiaddr::Multiaddr;
 pub use self::muxing::StreamMuxer;
 pub use self::peer_id::PeerId;
 pub use self::public_key::PublicKey;

core/src/transport/memory.rs

@@ -20,7 +20,7 @@
 
 use bytes::{Bytes, IntoBuf};
 use futures::{future::{self, FutureResult}, prelude::*, stream, sync::mpsc};
-use multiaddr::{AddrComponent, Multiaddr};
+use multiaddr::{Protocol, Multiaddr};
 use parking_lot::Mutex;
 use rw_stream_sink::RwStreamSink;
 use std::{io, sync::Arc};
@@ -132,7 +132,7 @@ impl<T: IntoBuf + Send + 'static> Transport for Listener<T> {
 /// Returns `true` if and only if the address is `/memory`.
 fn is_memory_addr(a: &Multiaddr) -> bool {
     let mut iter = a.iter();
-    if iter.next() != Some(AddrComponent::Memory) {
+    if iter.next() != Some(Protocol::Memory) {
         return false;
     }
     if iter.next().is_some() {