--use_jacobi
--allow_opencl_cpu
b3LauncherCL constructor takes string, to make it easier to determine failing OpenCL kernel
b3SetCustomErrorMessageFunc, printf error and exit(0)
remove duplicate data in b3Contact4 (now in btContact4Data shared between CPU/C++ and OpenCL)
OpenCL kernels use #include "Bullet3Collision/NarrowPhaseCollision/shared/b3Contact4Data.h"
Increase number of batches back to 250 (from 50), need to fix this hard coded number (see https://github.com/erwincoumans/bullet3/issues/12)
Work towards GJK/EPA, in addition to SAT/clipping (early on)
