Make valuator initialization modular

We no longer have only a single source for valuator data so the boundaries
are not fixed, either. Therefore, pass the boundaries as arguments and
check during initialization which mode we currently use.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Implement proper accel-based motion emulation

Use more advanced history-tracking to properly implement motion emulation
based on the accelerometer.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>