The Bullet 3.x B3_PROFILE can be customized using b3SetCustomEnterProfileZoneFunc/b3SetCustomLeaveProfileZoneFunc defined in Bullet3Common/b3Logging,
so you can hook Bullet 3.x up to your profiler of choice.
The Demos3/BasicGpuDemo will show the Bullet 3.x timings inside the Bullet 2.x btQuickprof profiler.
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)
