Initial release

Essentially Phoboslab's 2.1 release but using OpenVR instead of the Oculus SDK. This release includes his config files plus the shareware PAK0.pak.

Changes

• Enabling VR automatically executes vr_autoexec.cfg if it's located in the id1 directory, useful if you want some cvars to be changed for VR mode only.
• Added vr_viewkick to toggle view kick from player damage and gun firing.
• Removed vr_perfhud since OpenVR doesn't have a similar function.
• Removed view bob and roll when VR is enabled.