Mangalife indexes: support series with different seasons (chapter-1-index-2)

[jneidel]

Some manga on mangalife (see example: Tower of God) are split up in seasons.

Url parsing: These currently cannot be downloaded as the url parser for mangalife does not support this url structure: https://mangalife.us/read-online/Tower-Of-God-chapter-1-index-2-page-1.html

manga object: The index (if >=2) has to be added to the manga object and the history. In the history the index should be appended to the name:

• season 1/default: tower-of-god
• season 2/index 2: tower-of-god-s2 In reading the history this process should be reversed (i.e. read s2 at end of name as index).

Download process: While downloading on mangalife if the download fails (test which error) while there are still more chapters available, try raising the index (to 2 if normal download, to 3 if index=2, etc).