High/Low DPI Adapting

The Qt UI would change the size according to the logical DPI of the computer
Only Windows and Linux have been tested. (Should also work on Mac but have not tested).
The function is unfinished.

Fixes #576 
Hrm, can you find out how many times `.setMinimumSize(...)` is being called in each case? Maybe there's some kind of side effect that happens with repeated calls to it?