New tvheadend42 addon available from the addons folder - you may need to uninstall your existing version, as apparently it's not possible to upgrade from tvheadend v4.0 to tvheadend v4.2.
Texture Cache Maintenance Utility: Preload your texture cache for optimal UI performance. Remotely manage media libraries. Purge unused artwork to free up space. Find missing media. Configurable QA check to highlight metadata issues. Aid in diagnosis of library and cache related problems.