Update getChapterUrls() for mtlnovel site changes

See: dteviot#323

Add "Skip Images" option

Refer dteviot#321
Note, at this point no attempt has been made to deal with conflicts
with other features.
E.g. it doesn't work for Baka-Tsuki

Remove duplicate paragraphs from Wattpad

Fixes: dteviot#320

NovelsRock, fetch correct chapter URLs

Some ToC pages have two URLs for each chapter.
One with title of chapter and other with image.
Select the URL with the title.

Fixes: dteviot#317

Get all content for NovelsRock chapters

Sometimes not all chapter content is in <div class="reading-content">
element
Fixes: dteviot#316

Add DarkNovelsParser

Refer: dteviot#311

Track Babelnovel changes

dteviot#310

Update BabelChain Parser

See: dteviot#300

Rate limit BabelNovel site

Refer: dteviot#300

Bugfix: Chrome saving epub with .zip suffix

Suspect problem due to blob having mime type for zip file.
Changed to mime type for epub.
Resoves: dteviot#297