Clean up directory structure (#426)

* Remove unused circular-buffer crate
* Move transports into subdirectory
* Move misc into subdirectory
* Move stores into subdirectory
* Move multiplexers
* Move protocols
* Move libp2p top layer
* Fix Test: skip doctest if secio isn't enabled

protocols/floodsub/rpc.proto

@@ -0,0 +1,47 @@
+package floodsub.pb;
+
+message RPC {
+	repeated SubOpts subscriptions = 1;
+	repeated Message publish = 2;
+
+	message SubOpts {
+		optional bool subscribe = 1; // subscribe or unsubcribe
+		optional string topicid = 2;
+	}
+}
+
+message Message {
+	optional bytes from = 1;
+	optional bytes data = 2;
+	optional bytes seqno = 3;
+	repeated string topicIDs = 4;
+}
+
+// topicID = hash(topicDescriptor); (not the topic.name)
+message TopicDescriptor {
+	optional string name = 1;
+	optional AuthOpts auth = 2;
+	optional EncOpts enc = 3;
+
+	message AuthOpts {
+		optional AuthMode mode = 1;
+		repeated bytes keys = 2; // root keys to trust
+
+		enum AuthMode {
+			NONE = 0; // no authentication, anyone can publish
+			KEY = 1; // only messages signed by keys in the topic descriptor are accepted
+			WOT = 2; // web of trust, certificates can allow publisher set to grow
+		}
+	}
+
+	message EncOpts {
+		optional EncMode mode = 1;
+		repeated bytes keyHashes = 2; // the hashes of the shared keys used (salted)
+
+		enum EncMode {
+			NONE = 0; // no encryption, anyone can read
+			SHAREDKEY = 1; // messages are encrypted with shared key
+			WOT = 2; // web of trust, certificates can allow publisher set to grow
+		}
+	}
+}