First changes to use barriers
Removed functions sendText(), receiveText().
Changed callback signature from zmq::socket to SocketAdaptor.
Added lock()/unlock() to send/recv() functions.
Don't know if that explicti lock-unlock can cause troubles.
Don't know if add more lock/unlock to other methods like
listener-thread-main(), bind(), connect().
minor edit
Added suport to 'inproc' transport. Example of it (bank).
It needs to share context between sockets.
minor edit
minor edit
minor edit
Merge branch 'threadSafety'

Conflicts:
	README.md
minor edit