2.83.5
add the 'extras' and Bullet 2 tests, to make it easier to create a new intermediate release
fix HACD crash, thanks to gjaegy See https://github.com/bulletphysics/bullet3/pull/277
Auto limitation of spring stiffness and damping in btGeneric6DofSpring2Constraint is now optional. Fix: spring stiffness limitation used the mass incorrectly in btGeneric6DofSpring2Constraint.
rename ObsoleteDemos back to Demos fix some relative path issues for loading assets