Review cleanup

- Add constructors for ConnIDKey, remove BuildConnIDKey()
- Rename protocol stats classes and move to implementation file
- Rename "num" field of protocol stats to "active"
- Explicitly delete copy operations for SessionKey
- Change argument for ProtocolStats methods to const-reference
- Make key validity methods in Session not be virtual
- Rename Session::ClearKey and Session::IsKeyValid

src/Conn.cc

@@ -28,11 +28,9 @@ uint64_t Connection::current_connections = 0;
 Connection::Connection(const detail::ConnIDKey& k, double t,
                        const ConnID* id, uint32_t flow, const Packet* pkt)
 	: Session(t, connection_timeout, connection_status_update,
-	          detail::connection_status_update_interval)
+	          detail::connection_status_update_interval),
+	  key(k)
 	{
-	key = k;
-	key_valid = true;
-
 	orig_addr = id->src_addr;
 	resp_addr = id->dst_addr;
 	orig_port = id->src_port;