Allow reading of directly downloaded folders.

[ArbitraryFox]

这个功能是用来解决问题的吗？ / Is your feature request related to a problem? Please describe.
描述这个问题。
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

When I download directly to PC and put folder into EHviewer, the app doesn't recognize it.

描述你想要的解决方法 / Describe the solution you'd like
描述应通过何种行为来解决这个问题。
A clear and concise description of what you want to happen.

Make the app recognize the files and import into the reader.

备注 / Additional context
还有别的想说的吗？
Add any other context or screenshots about the feature request here.
Downloaded directly from ehentai and from app has different format.
The app should also read folder content when direct download from ehentai.