Changes in user interface

Renamed "display position monitoring" to "device state monitoring", and
renamed all variables, methods and messages accordingly. Renamed the
orientation changes, from "left" to "orientation left" etc., and renamed
their messages accordingly. Reordered buttons in the GUI.
Re-enabled stylus proximity monitoring by default

Turns out, there is no palm rejection in Ubuntu after all. Stylus
proximity monitoring is therefore re-enabled by default, and the README
edited accordingly.
Changed order of buttons in the GUI

Laptop mode before tablet mode, and normal and inverted orientation
before left and right orientation, feels more natural. The order of
methods in the code were changed according to a similar logic.