[statistics] get screen resolution(s)

[jflesch]

Collecting screen resolution(s) of users could help when designing the UI.

[jflesch]

https://askubuntu.com/questions/153549/how-to-detect-a-computers-physical-screen-size-in-gtk
https://askubuntu.com/a/303754

[tYYGH]

See also #548 (comment)
Just to say that the screen resolution is not always the window size ;-)
(Which is why I am so annoyed when Gtk applications like Evince get wider and wider each time…)

[jflesch]

That's a good point. Still, always better to have too much info than not enough :)

[jflesch]

Actually, we can get both: screen resolutions + window size.