introduce and use maxContactCapacity (needs to be fixed in various other contact kernels)
implement sphere versus trimesh
disable new/sequential GPU batching (only uses 1 thread in a warp, slow but works on NVIDIA/Apple OpenCL)
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
start adding various scenes to test gpu rigid body pipeline
reserve more memory for shapes (concave triangle mesh can be huge) in GLInstancingRenderer
fix a few crashes when 0 objects
