Add an enum for configuration return codes

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Add an interface to enable/disable tapping

Provide an interface to enable/disable tapping, with a default mapping of
1/2/3 fingers mapping to L/R/M button events, respectively.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
touchpad: hook up to the tapping configuration

Now that we have run-time changes of the tap.enabled state move the check
to the IDLE state only. Otherwise the tap machine may hang if tapping is
disabled while a gesture is in progress.

Two basic tests are added to check for the tap default setting - which is now
"tap disabled by default", for two reasons:
* if you don't know that tapping is a thing (or enabled by default), you get
  spurious button events that make the desktop feel buggy.
* if you do know what tapping is and you want it, you usually know where to
  enable it, or at least you can search for it.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
touchpad: reduce button size, use physical sizes where possible

The current 20% is excessive. On the t440s, the button size amounts to ~14mm
from the bottom. On the x220 it amounts to ~9mm, leaving only 31mm as actual
touchpad.

Reduce it to 15% instead, which amounts to 10.5mm on the t440 and 6mm on the
x220. Cap the button height further by making buttons a maximum height of
10mm, anything larger than that is excessive anyway.

Smaller buttons should be acceptable since we can rely on the bottom edge to
be a haptic feedback and thus a good hit-target, somewhat simliar to how
screen edges are good hit-targets.

The top software buttons stay the same size, but prefer a physical size of 6mm
instead (which is 1mm below the button marker line on the T440s). If no y
resolution is available, fall back to the 8% which is 5.6mm on the T440s.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
touchpad: drop the BOTTOM_TO_AREA/BOTTOM_NEW states

The original intention of this state was to prevent an accidental move out of
the bottom software button to start moving the cursor. That ends up actually
preventing a number of normal moves that start low enough. Simply drop the
state.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>