glkvm-web-enhancements

Cut a versioned release of the GLKVM Web Enhancements extension — bump the version in the two places that must match, regenerate the popup screenshot, ship, push, and publish a GitHub release. Use when the user asks to release, cut a release, publish a new version, or bump the extension version (e.g. "/release", "/release 1.1.0", "release a patch").