update to OpenVR sdk 1.03 from https://github.com/ValveSoftware/openvr
add camPosX/Y/Z and camRotZ to adjust relative camera/world transform for VR (so you can align virtual table with real table etc)
tweak quadruped.py to move a bit
add mouse picking to physics server
Add option to have Z as up-axis for VR examples.
Add OpenVR LICENSE + README file
Don't crash VR app when no HMD is detected, just exit.
For now, don't request debug lines in client, it slows down physics server in VR mode too much.