FEATURE: Implement per-stroke Fuzzy sensor
This patch also does a significant refactoring in the sensors
computation framework. Now the Fuzzy sensors work correctly with
Rotation, Hues, Saturation and Value options.
The fuzzy sensor's curve is divided into tho halves: the leftmost part
controls the negative offsets, the rightmost --- positive ones. Therefore
you can control if your fuzzy sensor increases the output or decreases it.
Please take into account that this rule works only for "relative" options,
that is for Rotation, Hue, Saturation and Value.
Ref T166
CC:kimageshop@kde.org