Add fragment_cache helper. Add cache option for partial helper.
Add helpers: image_tag, favicon_tag, feed_tag
Update helpers: link_to, mail_to
Update tests
Add url_for helper
Add global variable: `hexo.env.args` for cli arguments
util.format.strip_html is renamed to util.format.stripHtml
New filter type: server_middleware
If root url is not `/`, redirect to the correct root url
Backtick code block: fix remove non-space indentations
external_link filter: disable decodeEntities option of cheerio. Fix #666
post.create: don't render scaffold content with Swig. Fix #661
util.yfm: add a private method "split"
Update dependencies
2.6.3 released
Merge branch 'dev'
Apply url_for helper to other helpers
Response static file requests containing query string
Merge pull request #672 from hulufei/master

Handling static file requests containing query string
Merge branch 'master' into dev
Merge branch 'feature/relative-link' into dev

Conflicts:
	test/blog/package.json
Merge branch 'feature/fragment-cache' into dev