ZMQII-72: Add zmq_version function (documentation)

doc/Makefile.am

@@ -2,8 +2,8 @@ MAN1 = zmq_forwarder.1 zmq_streamer.1 zmq_queue.1
 MAN3 = zmq_bind.3 zmq_close.3 zmq_connect.3 zmq_flush.3 zmq_init.3 \
     zmq_msg_close.3 zmq_msg_copy.3 zmq_msg_data.3 zmq_msg_init.3 \
     zmq_msg_init_data.3 zmq_msg_init_size.3 zmq_msg_move.3 zmq_msg_size.3 \
-    zmq_poll.3 zmq_recv.3 zmq_send.3 zmq_setsockopt.3 zmq_socket.3 zmq_strerror.3 \
-    zmq_term.3
+    zmq_poll.3 zmq_recv.3 zmq_send.3 zmq_setsockopt.3 zmq_socket.3 \
+    zmq_strerror.3 zmq_term.3 zmq_version.3
 MAN7 = zmq.7 zmq_tcp.7 zmq_udp.7 zmq_pgm.7 zmq_inproc.7 zmq_ipc.7 \
     zmq_cpp.7 zmq_java.7 zmq_python.7
 MAN_DOC = $(MAN1) $(MAN3) $(MAN7)

doc/zmq_version.txt

+zmq_version(3)
+==============
+
+
+NAME
+----
+zmq_version - reports 0MQ version
+
+
+SYNOPSIS
+--------
+'void zmq_version (int *major, int *minor, int *patch);'
+
+
+DESCRIPTION
+-----------
+Returns current version of 0MQ. The functionality is useful for applications
+linking with 0MQ dynamically to make sure the right version of 0MQ is installed
+on the system.
+
+RETURN VALUE
+------------
+There is no return value.
+
+
+ERRORS
+------
+No errors are defined.
+
+
+EXAMPLE
+-------
+----
+int major, minor, patch;
+zmq_version (&major, &minor, &patch);
+printf ("Current 0MQ version is %d.%d.%d\n", major, minor, patch);
+----
+
+
+SEE ALSO
+--------
+linkzmq:zmq[7]
+
+AUTHOR
+------
+Martin Sustrik <sustrik at 250bpm dot com>