Add support for danbooru powered image boards SUG

[wightwulf1944]

check these imageboards. They use or are based off of danbooru so they might have the same underlying code.

warning, links are NSFW

http://chan.sankakucomplex.com/
http://danbooru.donmai.us/post
http://konachan.com/post

[bugmen0t]

There is a user script for (chan|idol).sankakucomplex.com. It still works but not without issues:

• the script sometimes triggers Thumbnail Zoom Plus zooming
• doesn't work with idol.sankakucomplex.com (white rectangle)
• original image loads too slowly unlike resized version (absurdres tag)
• with recent site update both galleries often show redirect.png if you hover over thumbnails too fast

So, the most common case is probably thumbnail.jpg -> resized.jpg e.g.,

// (chan|idol).sankakucomplex.com
// http://c4.sankakustatic.com/data/preview/47/1f/471fefb740c98c9657e7dfc6c0148cbb.jpg becomes
// http://c4.sankakustatic.com/data/sample/47/1f/preview471fefb740c98c9657e7dfc6c0148cbb.jpg
aImageSrc = aImageSrc.replace(new RegExp(
          "(sankakustatic.com/data)/preview" +
          "((/[0-9a-f]{2}){2})" +
          "/([0-9a-f]+" +
          EXTS + ")", "i"),
          "$1/sample$2/preview$4");

GIFs and lowres images need a fallback method to fetch original as there is no resized version.