Improve dead-band and non-linear band

[norihiro]

Current dead-band implementation is modifying the error amount before the PID filter.
It results in PTZ moving while the face is detected inside the dead-band because the integral portion of the PID filter can be non-zero.

Instead of just modifying the error amount, the proposal is to force-stop the camera.

The idea was originally suggested by a DM from toplachi, and the reference of the competitor's work is available on YouTube video.