Next release may surprise shynet users due to GPC header

[haaavk]

GPC header is treated the same as DNT header right now.
DNT is deprecated and rarely used compared to GPC.
People may not know they are using it (I didn't know).
For example Brave browser and DuckDuckGo Privacy Essentials extension set GPC header.
After next release shynet users may be suprised (I was) they don't see their own visits.
The first test I do after deploying new version is to visit one of my websites and see the spike in dashboard.
It took me a while to understand why there is no spike.