Support High-DPI displays

[keirlawson]

Is your feature request related to a problem? Please describe.
As a user with a 4k laptop display I struggle to read the UI as it does not seem to take into account the high DPI nature of the screen, unlike the rest of my desktop

Describe the solution you'd like
It would be great if Insulator could support high DPI displays

Describe alternatives you've considered
None

Additional context
I'm using GNOME with Wayland on Ubuntu Linux