OpenVR support with basic VR preset

Includes the improvements in the main Reshade repository as well as a few additional fixes:

• effects in the headset now reflect config changes made in the UI immediately
• don't apply effects to the window (unless the UI is open) to not waste GPU performance

This ZIP includes a basic ready-to-go Reshade preset for VR games, aimed at Valve Index users. It includes a sharpening filter as well as basic color adjustment options (brightness, contrast, saturation) with default values chosen to combat washed out and blurry visuals in games with the Index. You can of course adjust these values or assemble your own preset to use with this build :)

Installation & usage instructions included in the README in the archive.