#1866 support for rule34.paheal.net

note: rule34.paheal.net runs shimmie
indent
Prevent pixiv downloader from returning wrong image
Add hint for renaming wikis/artists
#1866: support doujinantena source redirection

brings the user to the front/1st page of the doujin similar when viewing manga in pixiv
#1866 add new gem for base62 methods

the methods are encode62 and decode62

more info: https://github.com/matiaskorhonen/radix62
#1866 support rule34.xxx and img.ly

* included support for the old rule34 under the booru.org imageboard network
* img.ly uses base62 links e4146636af0770007b010fe2d5d7b531a7f8c5ac
#2211: the mishimmie support

runs shimmie
#2213: limited support for diarypro

doesn't support the following:
* those with customized subdirectories
* those that replaced the default diary.cgi with other page
* those that moved to other domains
* deleted or reset entry numbers
* domains that switched to other blog service provider
WebM support
#2215: update to fix the first case
Merge pull request #2214 from r888888888/webm

WebM support
fixes #2208
Remove old gemcutter.org source
fixes #2208
fixes #2215 hopefully

* improved domain support
* renamed archived files will be redirected to the latest version; users still have to click 'File history' to view the old ones

note: it appears wikia doesn't support yet #filehistory and #mediaviewer from wikipedia
#1866: improved gelbooru support

* support for discontinued sha1 naming scheme
* all redirects to gelbooru will now use danbooru's md5 hashes
* update for aa7a91c98f6a9ca1edbbc331d1e92b16fd2d7cf1
update #2216 for old urls

* follow-up to b194935bdeb4950180926b93817e3cf975659e82
* doesn't solve the parentheses problem
Add icon indicating post is animated
fixes #2217