Add calibration for x sensitivity and y sensitivity

[Adam-McDevitt]

Currently the user must manually configure these. Some sort of calibration function would be good.

For example, the eyes would be set to look all the way to the left, and the user is then asked to move their face to a position where it appears that the eyes are looking at them. From this information, the x and y sensitivity can be derived. They would be set to the values such that, when the user stands in that same position, the eye looks all the way to the left/

The user should still be able to configure these options manually if they want to.