EasyViewer-PDF,epub,heic,Tiff

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- Fix epub-css parser
- Fix image zoom
- Fix thumbnail generation
- Fix light theme error (Thanks to 박체채)
- Add a menu to change/delete thumbnails (Thanks to Sue Shin)
Click the [...] button in the file list to run
You can change to the desired thumbnail
- Fix TTS control button bug (Thanks to 허얼얼)

* Change log
- epub improvements
Fix epub parser
Fix image cache
- Fix file deletion permission bug (Thanks to debbiexx2)
- Improved compatibility with Android 8, 9