defaults.xml
Set new property /sim/mouse/mouse-rudder-elevator to false, but with
userarchive="y".
gui/dialogs/input-config.xml
Added checkbox to control /sim/mouse/mouse-rudder-elevator.
mice.xml:
Allow mouse control of elevator with button 0 down if
/sim/mouse/mouse-rudder-elevator is true.
Replace the temporary UI with real solutions, in the view dialog
(for tooltips/popups) and a new 'input config' dialog accessed via
the file menu.
Make the mouse-cycle popup explicitly optional since some people
strongly dislike it.
