PRICE - image filtering and manipulation Code

do not scale if we have no sender

some better checks, asserts and minor fixes

Make changing channels in RGB correctly set the current black and white point

draw curves and histogram in a preferred order so that the selected one is always on top

size exactly 255x255

make view exactly 255 px wide and hight, make the view resizable

use max normal size for calculation, transformation is applied later, the size is not important anymore

use a macro to define control point rects and make them 2 pixels larger

fix resizing and calculation of the affinte transform, use bounds for it; reset the curve transformation when resetting it

Allow the curves's total transformation to be reset