Fix ball/compound intersection test + 2D convex hull orientation

[sebcrozet]

Modified

• Until now, the orientation of the polygon computed by 2D convex hull computation parry2d::transformation::convex_hull and
  parry2d::transformation::convex_hull_idx wasn't specified (and was generally in clockwise order). Now, this
  orientation is explicitly specified in the documentation and is set to counter-clockwise order (which is coherent
  with orientation expected by, e.g., the ConvexPolygon type).

Fixed

• Fix the orientation of the polygons generated by the 2D convex polygon decomposition (they are now always oriented
  counter-clockwise as expected by the ConvexPolygon type).
• Fix the intersection test between a 2D ball and a 2D compound shape.