Problem: zmq_connect with IPv6 "source:port;dest:port" format is broken

Solution: allow for '[' character when doing the basic sanity check
on the TCP endpoint.
Also add unit tests for both IPv4 and IPv6 source;dest format.

src/socket_base.cpp

@@ -843,7 +843,7 @@ int zmq::socket_base_t::connect (const char *addr_)
             while (isalnum  (*check)
                 || isxdigit (*check)
                 || *check == '.' || *check == '-' || *check == ':' || *check == '%'
-                || *check == ';' || *check == ']' || *check == '_'
+                || *check == ';' || *check == '['  || *check == ']' || *check == '_'
             ) {
                 check++;
             }

tests/test_reqrep_tcp.cpp

@@ -88,7 +88,7 @@ void test_multi_connect_ipv4 (void)
     assert (rc == 0);
     rc = zmq_connect (sc, "tcp://127.0.0.1:5561");
     assert (rc == 0);
-    rc = zmq_connect (sc, "tcp://127.0.0.1:5562");
+    rc = zmq_connect (sc, "tcp://127.0.0.1:5564;127.0.0.1:5562");
     assert (rc == 0);
 
     bounce (sb0, sc);
@@ -101,7 +101,7 @@ void test_multi_connect_ipv4 (void)
 
     rc = zmq_disconnect (sc, "tcp://127.0.0.1:5560");
     assert (rc == 0);
-    rc = zmq_disconnect (sc, "tcp://127.0.0.1:5562");
+    rc = zmq_disconnect (sc, "tcp://127.0.0.1:5564;127.0.0.1:5562");
     assert (rc == 0);
     rc = zmq_disconnect (sc, "tcp://127.0.0.1:5561");
     assert (rc == 0);
@@ -214,7 +214,7 @@ void test_multi_connect_ipv6 (void)
     assert (rc == 0);
     rc = zmq_connect (sc, "tcp://[::1]:5561");
     assert (rc == 0);
-    rc = zmq_connect (sc, "tcp://[::1]:5562");
+    rc = zmq_connect (sc, "tcp://[::1]:5564;[::1]:5562");
     assert (rc == 0);
 
     bounce (sb0, sc);
@@ -227,7 +227,7 @@ void test_multi_connect_ipv6 (void)
 
     rc = zmq_disconnect (sc, "tcp://[::1]:5560");
     assert (rc == 0);
-    rc = zmq_disconnect (sc, "tcp://[::1]:5562");
+    rc = zmq_disconnect (sc, "tcp://[::1]:5564;[::1]:5562");
     assert (rc == 0);
     rc = zmq_disconnect (sc, "tcp://[::1]:5561");
     assert (rc == 0);