Added support for non-zmq tcp client connections to router socket.

- Created a new option ZMQ_ROUTER_RAW_SOCK
    - Added new raw_encoder and raw_decoder to receive and send messages in raw form to remote client
    - Added test case file tests/test_raw_sock.cpp

    o To create a raw router sock set the ZMQ_ROUTER_RAW_SOCK option
    o ZMQ_MSGMORE flag is ignored for non-id messages
    o To terminate a remote connection send id message followed by zero length data message

src/decoder.hpp

@@ -143,6 +143,11 @@ namespace zmq
             }
         }
 
+        inline bool message_ready_size (size_t msg_sz){
+            zmq_assert(false);
+            return false;
+        }
+
     protected:
 
         //  Prototype of state machine action. Action should return false if