refactor: circuit relay to async (#477)

* refactor: add dialing over relay support

* chore: fix lint

* fix: dont clear listeners on close

* fix: if dial errors already have codes, just rethrow them

* fix: clear the registrar when libp2p stops

* fix: improve connection maintenance with circuit

* chore: correct feedback

* test: use chai as promised

* test(fix): reset multiaddrs on dial test

test/transports/transport-manager.node.js

@@ -38,11 +38,12 @@ describe('Transport Manager (TCP)', () => {
   it('should be able to listen', async () => {
     tm.add(Transport.prototype[Symbol.toStringTag], Transport)
     await tm.listen(addrs)
-    expect(tm._listeners.size).to.equal(1)
+    expect(tm._listeners).to.have.key(Transport.prototype[Symbol.toStringTag])
+    expect(tm._listeners.get(Transport.prototype[Symbol.toStringTag])).to.have.length(addrs.length)
     // Ephemeral ip addresses may result in multiple listeners
     expect(tm.getAddrs().length).to.equal(addrs.length)
     await tm.close()
-    expect(tm._listeners.size).to.equal(0)
+    expect(tm._listeners.get(Transport.prototype[Symbol.toStringTag])).to.have.length(0)
   })
 
   it('should be able to dial', async () => {