Brown paper bag fix: forgot to update the cavariance matrix.

Signed-off-by: Jean-Yves Tinevez <jeanyves.tinevez@gmail.com>
The Kalman filter returns an estimate of the pos and velocity error.

Signed-off-by: Jean-Yves Tinevez <jeanyves.tinevez@gmail.com>
Another interactive test for the Kalman tracker.

Signed-off-by: Jean-Yves Tinevez <jeanyves.tinevez@gmail.com>