make the super-keyboard work on desktop

[digama0]

You can't use the keyboard when not in VR currently. There is a debug setting DEBUG_KEYBOARD that allows you to click on the buttons manually it but this breaks it in VR, because it just switches the input method and then the laser pointers don't work. This is not a perfect implementation since it doesn't disable the usage of keys for other things (e.g. pressing 'A' will cause you to walk to the left and also type an 'A' in the keyboard), but at least it isn't unusable.