add b3QHull object

b3QHull allows users to create hull shapes from a list of points quickly. Example usage:

vec3* points = 0;
uint count = create_points(points);

b3QHull hull;
hull.Set(points, count);

include/bounce/bounce.h

@@ -36,6 +36,7 @@
 #include <bounce/collision/shapes/capsule.h>
 #include <bounce/collision/shapes/hull.h>
 #include <bounce/collision/shapes/box_hull.h>
+#include <bounce/collision/shapes/qhull.h>
 #include <bounce/collision/shapes/mesh.h>
 #include <bounce/collision/shapes/grid_mesh.h>