GUI: prepare for a per-channel oscilloscope?

currently supported systems:
- Amiga
- AY-3-8910
- Dummy System
- OPLL
- SegaPCM

no trigger supported yet!

src/gui/doAction.cpp

@@ -217,6 +217,9 @@ void FurnaceGUI::doAction(int what) {
     case GUI_ACTION_WINDOW_EFFECT_LIST:
       nextWindow=GUI_WINDOW_EFFECT_LIST;
       break;
+    case GUI_ACTION_WINDOW_CHAN_OSC:
+      nextWindow=GUI_WINDOW_CHAN_OSC;
+      break;
     
     case GUI_ACTION_COLLAPSE_WINDOW:
       collapseWindow=true;
@@ -295,6 +298,9 @@ void FurnaceGUI::doAction(int what) {
         case GUI_WINDOW_EFFECT_LIST:
           effectListOpen=false;
           break;
+        case GUI_WINDOW_CHAN_OSC:
+          chanOscOpen=false;
+          break;
         default:
           break;
       }