Code cleanup

std::map::insert() has always had range based insertion, removed
explicit loops.

src/stream_engine.cpp

@@ -813,19 +813,11 @@ void zmq::stream_engine_t::mechanism_ready ()
 
     //  Add ZAP properties.
     const properties_t& zap_properties = mechanism->get_zap_properties ();
-    it = zap_properties.begin ();
-    while (it != zap_properties.end ()) {
-        properties.insert (properties_t::value_type (it->first, it->second));
-        ++it;
-    }
+    properties.insert(zap_properties.begin(), zap_properties.end());
 
     //  Add ZMTP properties.
     const properties_t& zmtp_properties = mechanism->get_zmtp_properties ();
-    it = zmtp_properties.begin ();
-    while (it != zmtp_properties.end ()) {
-        properties.insert (properties_t::value_type (it->first, it->second));
-        ++it;
-    }
+    properties.insert(zmtp_properties.begin(), zmtp_properties.end ());
 
     zmq_assert (metadata == NULL);
     if (!properties.empty ())