Squashed 'extensions/DFDiagram/' changes from 5818b6e..8696bb3

8696bb3 Fix CSS when JS is disabled

git-subtree-dir: extensions/DFDiagram
git-subtree-split: 8696bb3ad89bcbc73bdaa4b37c5fac40e91d40c2
Update DFDiagram (0.5)

Merge commit 'a57f4be903938791f5975dbab64b347dfa6338bc'