Replace GraphicsMagick with Imager module
Add category manager page (can set some author/topic to inactive, hiding it)
Add a simple JS RSS aggregator (it needs an upstream with CORS, like amusewiki sites)
Add autocomplete on the layout search box
Add spelling corrections on search
Add the apple-touch-icon (using the opengraph.png file).
After a lot of wondering, the system call to GraphicsMagick have been removed. GM is probably safer than IM, but on the other hand it has too many features which we don't need and a larger attack surface. Plus working with a module is more flexible than shelling out.
The PDF thumbnailing is now a call to Ghostscript (which is what GM was doing anyway).
However, the Imager module requires system libraries to be installed properly. There is a check on startup to assert you're covered. Otherwise refer to Imager::Install if in doubt.