Bug: 5265529
Rewrote the velocity tracker to fit a polynomial curve
to pointer movements using least squares linear regression.
The velocity is simply the first derivative of this polynomial.
Clients can also obtain an Estimator that describes the
complete terms of the estimating polynomial including
the coefficient of determination which provides a measure
of the quality of the fit (confidence).
Enhanced PointerLocation to display the movement curve predicted
by the estimator in addition to the velocity vector.
By default, the algorithm computes a 2nd degree (quadratic)
polynomial based on a 100ms recent history horizon.
Change-Id: Id377bef44117fce68fee2c41f90134ce3224d3a1
73aaf0d8d2