Revert "Revert "Merge branch 'master' of github.com:ianbarber/libzmq""

This reverts commit 029d3dfae2.

src/session_base.hpp

@@ -104,8 +104,8 @@ namespace zmq
         //  Pipe connecting the session to its socket.
         zmq::pipe_t *pipe;
         
-        //  Socket end of the pipe, for delay attach scenario
-        zmq::pipe_t *outpipe;
+        //  This flag is set if we are disconnecting, but haven't yet completed
+        int incomplete_detach;
 
         //  This flag is true if the remainder of the message being processed
         //  is still in the in pipe.