fix(RadialMenu): apply correct rotation offset to menu

The radial menu offset rotation was inverted causing issues when
pressing the touchpad as the touch position was not in the same
location as the button position.

This fix inverts the touch coordinate to ensure it matches the
button position.

Assets/VRTK/Scripts/Controls/2D/RadialMenu/RadialMenu.cs

@@ -100,7 +100,7 @@ private void InteractButton(float angle, ButtonEvent evt) //Can't pass ExecuteEv
         {
             //Get button ID from angle
             float buttonAngle = 360f / buttons.Count; //Each button is an arc with this angle
-            angle = mod((angle + offsetRotation), 360); //Offset the touch coordinate with our offset
+            angle = mod((angle + -offsetRotation), 360); //Offset the touch coordinate with our offset
 
             int buttonID = (int)mod(((angle + (buttonAngle / 2f)) / buttonAngle), buttons.Count); //Convert angle into ButtonID (This is the magic)
             var pointer = new PointerEventData(EventSystem.current); //Create a new EventSystem (UI) Event