Optional: Vulkan rendering for the game client.

1. Download a DXVK release from https://github.com/doitsujin/dxvk/releases
2. Open the archive and go into the x32 folder (the SWG client is 32-bit).
3. Copy d3d9.dll from x32 into this folder, so it sits at dxvk\d3d9.dll.

When the file is present, the "Use Vulkan rendering (DXVK)" option in the
launcher's Settings becomes available. Without it, the option is greyed out.
DXVK is licensed under the zlib license, which allows shipping it with the launcher.
