* Rename "DownloadedFilesProvider" to "ChaptersFilesProvider"
* Move files into sub packages
* Further abstract "DownloadedFilesProvider"
* Rename "getCachedImageResponse" to "getImageResponse"
* Extract getting cached image response into new function
* Decouple thumbnail cache and download
* Download and delete permanent thumbnails
When adding/removing manga from/to the library make sure the permanent thumbnail files will get handled properly
* Move thumbnail cache to actual temp folder
* Rename "mangaDownloadsRoot" to "downloadRoot"
* Move manga downloads into "mangas" subfolder
* Clear downloaded thumbnail
* Add "server" to "checkForUpdate" logic names
* Use "webUIRoot" as default path for "getLocalVersion"
* Use local version as default version for "isUpdateAvailable"
* Return the version with the webUI update check
* Update WebinterfaceManager to be async
* Add query, mutation and subscription for webUI update
* Catch error and return default error value for missing local WebUI version
* Improve default category handling and add cascade to references where possible
* Minor fix for default category
* Make the default category always first in the normalization
