* 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
* Support extensions lib 1.4
* Fix build
* Support UpdateStrategy
* Update extension lib min/max to match Tachiyomi
* Use HttpSource.getMangaUrl and add Chapter.realUrl
* Add lastFetchedAt and chaptersLastFetchedAt columns to manga
* Update lastFetchedAt columns when data are fetched from source
* Add age and chaptersAge fields to MangaDataClass
* Replace two migrations with single migration