Snap Objects - 6

Now there are only the implementations of the functions creating the functors for the minimization of the line and circle constraint missing and it should all be finished. At least until I start using it, as I assume I will find bugs in the code. So I guess I will have to do some more derivation and I still have to find an equation for the circles, I haven't really thought about how to do it. I think I will have to split it in two parts, minimizing the distance of the points from a line (the axis of a cylinder) and the distance from the circles plane. I think summing those two functions should work.