Mixer: Don't create/destroy OSC ports more often than necessary.

mixer/src/Module.H

@@ -351,6 +351,8 @@ public:
 
     Chain *chain ( void ) const { return _chain; }
     void chain ( Chain * v )
+        {
+            if ( _chain != v )
             {
                 _chain = v; 
 
@@ -359,6 +361,7 @@ public:
                     control_input[i].update_osc_port();
                 }
             }
+        }
 
     char *get_parameters ( void ) const;
     void set_parameters ( const char * );