Create second project for SteamVR: 2.6.1 (with Support for Unity <2018.1)

[JaXt0r]

When activating VR controllers in a Unity <2018.1, SteamVR Unity plugin can't be used with latest version (as it expects UnityEngine.VRModule with UnityEngine.XR namespace).

Therefore let's split projects:

• SteamVR-2.6.1
• SteamVR-latest

And add a new build config for Unity <mono-5.4-2017.4.40f1

Note

TODO: Check if gamemanager.asset from 5.0.x contains VR settings already. If so, it would be possible to use. If not, skip it.