Re-organize demo menu so that shutdown is first; add battery monitoring daemon
Created by: pavelmachek
On n900, postmarketos-demos is too high, and does not fit on screen. You can't even shutdown your machine cleanly. Fix it by putting shutdown first.
Normally, hardware is responsible for shutting down the system when battery is low. But N900 does not have such hardware, and kernel is not doing the job, either. Protect battery by shutting down when voltage drops too much.