Change-Id: Ib8376f846be86b46b9b4f347f04cce73f7d7e609
* Added ContentHandler facility to allow extensions to support other content than wikitext.
See docs/contenthandler.txt for details.
* $wgResponsiveImages is added to support images on high-DPI mobile and desktop displays.
+* Added new backend to represent and store information about sites and site specific configuration.
=== Bug fixes in 1.21 ===
* (bug 40353) SpecialDoubleRedirect should support interwiki redirects.