y() -> y or getY() or [1]
z() -> z or getZ() or [2]
w() -> w or getW() or [3]
make sphere-convex and sphere-compound collision work (still issues remaining)
added alternative batching kernel (slow)
tweaked controls a bit
added command-line options --selected_demo=<int> and --new_batching
started looking into parallel 3d sap
