Make qutebrowser work better with HDPI displays

[stevenroose]

I have a Dell XPS 15 with 4K display. While almost all applications that I run here (Arch with GNOME Shell) are very well adapted to the hdpi display, qutebrowser is not. Even though I can easily zoom in to 150%, the link tags ("f") are still displayed very small and hard for me to distinguish.

Since I couldn't find anything while searching for "hdpi" in the repo or on Google, I suppose this issue has not come up before.

[The-Compiler]

See #1585. Turning on Qt's automatic scaling (the equivalent to export QT_AUTO_SCREEN_SCALE_FACTOR=1) caused some trouble for some people, so I turned it off again. If setting that environment variable doesn't make any difference, you can still bump up the fonts in the config, e.g. via :set fonts hints for the hints (link tags).