Oculus Menu Button Input Binding Change

To support an upcoming Oculus / SteamVR button compatibility change the button binding to bring up the game menu has moved from app button to the Y button on the left controller. This is because the app button on the left controller will soon be reserved for use as the system button on Oculus compatible controllers. Similarly, the recenter button binding is now holding down the left Y button for 1 second, instead of holding the left app button.