The openvr/bin/linux64 directory also contained a file called empty.dir. This has been removed because it was an empty file. VREvent_Scroll has been renamed to VREvent_ScrollSmooth, and not VREvent_ScrollDescrete because the second one will keep scrolling after having let go of the scroll (tested on Vive controller). This feels weird when done on a Vive controller and so the first option was chosen. The first option also feels more like the old system. Even though the version jump is weird this is the next release.
OpenVR SDK
OpenVR is an API and runtime that allows access to VR hardware from multiple vendors without requiring that applications have specific knowledge of the hardware they are targeting. This repository is an SDK that contains the API and samples. The runtime is under SteamVR in Tools on Steam.
Documentation
Documentation for the API is available on the Github Wiki
More information on OpenVR and SteamVR can be found on http://steamvr.com