faster scene construction when not using instancing (avoid copy individual vertices/shapes to GPU, but do it afterwards in a batch), copy GPU data in 'writeAllBodiesToGpu' method
add option --no_instanced_collision_shapes, this only applies to the 2 benchmark screnes at the moment
always use the user specified b3Config file, so the settings can be set at runtime, not just at compile time
adjust default constants in b3Config (needs more tweaking, ideally at run-time)