Add DICOM Group 6xxx Overlay Plane rendering (#1402)

* Add DICOM Group 6xxx Overlay Plane rendering

* Bump to cornerstone-tools 4.12.0 to support DICOM 6xxx Overlays

extensions/cornerstone/src/init.js

@@ -98,6 +98,7 @@ export default function init({ servicesManager, configuration }) {
       csTools.MagnifyTool,
       csTools.StackScrollTool,
       csTools.StackScrollMouseWheelTool,
+      csTools.OverlayTool,
     ],
   };
 
@@ -179,4 +180,5 @@ export default function init({ servicesManager, configuration }) {
   csTools.setToolActive('StackScrollMouseWheel', {}); // TODO: Empty options should not be required
   csTools.setToolActive('PanMultiTouch', { pointers: 2 }); // TODO: Better error if no options
   csTools.setToolActive('ZoomTouchPinch', {});
+  csTools.setToolEnabled('Overlay', {});
 }