Cirrus updates for 1.24

This is literally just merging the master branch of Cirrus to the 1.24 release
branch. Almost everything just works. What doesn't:
1. Highlighting category matches - these are ignored
2. Auxiliary text items - these are just merged into the main article text

Change-Id: I7f66548f8213588bf758b6ef6b56ad5ad66fca08