Since multisource extensions are no longer a thing, we now simply rely on the flag at the extension level, i.e. the per-Source/SourceFactory `@Nsfw` annotation is no longer checked.
We'll have to remove all of the annotation usages from the existing sources, which will also effectively break the setting for older versions of the app.
* Allow multiple sources in each extension source apk
Minor code cleanup
* Add runtime defined sources functionality
* Undo extensions library major version number bump
* add local source
* small fixes
* change Chapter to SChapter and and Manga to SManga in ChapterRecognition.
Use ChapterRecognition.parseChapterNumber() to recognize chapter numbers.
* use thread poll
* update isImage()
* add isImage() function to DiskUtil
* improve cover handling
* Support external SD cards
* use R.string.app_name as root folder name
