"I've added a Plane constructor which accepts a normal and a point.
I also removed calculateUpperLowerBBCorners() from the Plane(const
Vec3& v1, const Vec3& v2, const Vec3& v3) since the constructor is
using the function set(const Vec3& v1, const Vec3& v2, const Vec3& v3)
which already computes the upper and lower bounding box."