Firmware 2v10 will disable touch/swipe while the LCD is off anyway, so
just enable them always. (but keeps the check that the LCD is on until
the whole world has upgraded their firmware)
Using BTN3-rising for `volumedown` meant that everytime you hold BTN3 to
reload the watch it first messes with your volume. So now we listen for
falling edge only.
Also add double/triple pressing BTN2 for next/previous.
And fix a bug with the scroller interval.