If the trackpoint gives us deltas with less than 10ms intervals, something is
wrong. Could be bad hardware, a glitch in the matrix or a discontinuity in
the otherwise appropriately named time-space continuum. Usually it's the
first.

Let's always set up trackpoint delta smoothening for 10ms to improve the
pointer speed calculation and avoid jerky behaviors. i.e. if a trackpoint
delta comes in below 10ms, pretend it came in with a 10ms interval for
calculating the speed.

Fixes #104



Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>