Be a bit smarter detecting XML?

[WhyNotHugo]

The config files for fontconfig are XML, but their extension if .conf.

It seems that even with this package installed, they're not recognised as xml (I guess it's based on extension and not the contents themselves?). Might it be possible to do filetype detection based on the header <?xml version="1.0"?>?

Is that something that this plugin should handle? Or is the problem that the dosini handler thinks the file is an ini due to extension?