access: public osmd.RenderingManager, sheetRenderingManager.setStartPosition + Listeners (#55)

part of #55, just the general use accessors part

src/Display/SheetRenderingManager.ts

@@ -35,6 +35,9 @@ export class SheetRenderingManager extends AbstractZoomView implements IZoomView
     public addListener(listener: IUserDisplayInteractionListener): void {
         this.listeners.push(listener);
     }
+    public get Listeners(): IUserDisplayInteractionListener[] {
+        return this.listeners;
+    }
     public SingleTouchDisabled: boolean;
     public DoubleTouchDisabled: boolean;
     public LockDisplayToCursor: boolean = true;
@@ -267,7 +270,7 @@ export class SheetRenderingManager extends AbstractZoomView implements IZoomView
         }
     }
 
-    protected setStartPosition(newStartPosition: Fraction): void {
+    public setStartPosition(newStartPosition: Fraction): void {
         if (this.graphicalMusicSheet === undefined) {
             return;
         }

src/OpenSheetMusicDisplay/OpenSheetMusicDisplay.ts

@@ -98,12 +98,15 @@ export class OpenSheetMusicDisplay {
     private disposeResizeListener: Function;
     protected followCursor: boolean;
     protected OnXMLRead: Function;
+
+    public get RenderingManager(): SheetRenderingManager {
+        return this.renderingManager;
+    }
     public set PlaybackManager(manager: PlaybackManager) {
         if (this.renderingManager) {
             this.renderingManager.PlaybackManager = manager;
         }
     }
-
     public get PlaybackManager(): PlaybackManager {
         return this.renderingManager?.PlaybackManager;
     }