Support ABP filter rule extensions

[pes10k]

Copied over from brave/ad-block#113

This would help squeeze out some more stuff out of the some of the filters that are already used and it would make it possible to implement even more filters in the future. The new syntax is an extension of ABP Filter Syntax and should (in theory) not be too hard to implement. More info on it can be found here: https://github.com/gorhill/uBlock/wiki/Static-filter-syntax#extended-syntax

In general, there is some value in supporting ABP specific additions, more so on network rules but possibly on cosmetic rules too. Low priority but would be "nice to have"