Instead of passing the same constant to LedDisplay_SetLayerLed() all the time,
lift it out into a global.
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
When switching layers, light up the appropriate LED on the display. For this
purpose, start led_display.[ch], which as a start, has a function to set the
brightness of a layer led.
The function will also turn all other LEDs off, and turn all of them off when on
the base layer.
Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
