[MATH-749] Improve robustness for convex hull algorithms in case of identical / collinear points, added flag whether to include only extreme points or all points on the hull, improve unit tests.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1564934 13f79535-47bb-0310-9956-ffa450edef68