media queries not included

[paulpflug]

hey,

your project inspired me, but my usecase is a bit out of scope, so I created my own package...

However, I found out, that CSS.takeCoverageDelta() doesn't include the media queries for a rule.
I tinkered a bit and outsourced the resulting parser in a separate package coverage-delta-parser. Feel free to use or copy, it is rather small..