VGM export: add "trailing ticks" option

issue #695

src/engine/playback.cpp

@@ -957,6 +957,8 @@ void DivEngine::processRow(int i, bool afterDelay) {
         }
       } else if (!chan[i].noteOnInhibit) {
         dispatchCmd(DivCommand(DIV_CMD_NOTE_ON,i,chan[i].note,chan[i].volume>>8));
+        chan[i].goneThroughNote=true;
+        chan[i].wentThroughNote=true;
         keyHit[i]=true;
       }
     }