Problem of affordance zone when using reduceSizes

[JasonChmn]

I created a hole in ground.stl and got this issue with the affordance zone.

The problem is that the affordance zone covers a part of the hole.
(Image above with reduceSizes=[0.18,0,0])
Not using the ReduceSize parameter in afftool.loadObstacleModel fix this problem.

[pFernbach]

The method creating the issue is this one :https://github.com/humanoid-path-planner/hpp-affordance/blob/master/src/affordance-extraction.cc#L181-L192
It looks like it can only work correctly for convex shapes in the current implementation.