BulletSim: improve avatar stair walking up. Add more parameters to control force
of both position change and up force that move avatars over barrier.
Default parameters are for steps up to 0.5m in height.
BulletSim: update DLLs and SOs to they have no dependencies on newer
glibc (2.14) since that is not yet in some Linux distributions.
Add unmanaged API calls and code for creating single convex hull shapes.
BulletSim: partial addition of BSShape class code preparing for
different physical mesh representations (simplified convex meshes)
and avatar mesh.