3.7.2
=====
* MathML support for Mallard and DocBook
* Audio and video support for DocBook
* Ability to set poster image for video
* TTML subtitles for audio and inline media
* Updated media controls
* Fixed #hash auto-expanding and colorizing
* Translator and publisher credits
* Use quote char on :before for blockquote
* ARIA landmark roles
* Changed marker for expanders
* Switched ui:expanded to non-experimental
* Experimental Mallard UI overlays
* Dropped unused DocBook utility XSLT
* Use itstool "join mode" for translations
* More experimental thumbnail link styles