Updated mediawiki/extensions
Project: mediawiki/extensions/MultimediaViewer  53a641b63a42c4e00a6335ce5bf930b0b6ef328a

Rename Buttons to CanvasButtons

Less misleading as we have lots of buttons, and I plan to add a new
button class for the Commons/survey/reuse thing.

Change-Id: I74194e22e9066c58f9c1eba57629458b2b9148b5