rework extension system and manga/chapter/page indentifier

[faldez]

• replace ron with bincode
• replace manga/chapter/page id with composite primary key for database flexibility e.g.
  • manga: (source_id, iid), iid is decided by extension
  • chapter: (source_id, manga_iid, iid), iid is decided by extension
  • page: (source_id, manga_iid, chapter_iid, rank)
• extension trait
  • get_manga_list
  • get_manga_details -> replacing get_manga_info
  • get_chapters
  • get_chapter_details -> replacing get_pages

[mathroc]

I don't know much about it but will that help implementing #226 or make it more complicated?

also: shouldn't source_id be extension_id ?

[faldez]

It should be the same. I was thinking this id system will be useful for clearing data/cache in database but still want to preserve reading history/library because it doesn't rely on id generated by database.

source_id is extension_id since 1 extension only contain 1 source