fix(Controller): ensure touchpad press status is set correctly

The Touchpad Press status was always being reported as pressed after
it had been released because the `Pointer Set` alias was incorrectly
setting it to true. This has now been fixed.

Assets/SteamVR_Unity_Toolkit/Scripts/VRTK_ControllerEvents.cs

@@ -312,7 +312,7 @@ private void EmitAlias(ButtonAlias type, bool touchDown, float buttonPressure, r
             {
                 if (! touchDown)
                 {
-                    OnAliasPointerSet(SetButtonEvent(ref buttonBool, true, buttonPressure));
+                    OnAliasPointerSet(SetButtonEvent(ref buttonBool, false, buttonPressure));
                 }
             }