Related #576 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.
No. But both Windows and Ubuntu consider the standard DPI as 96 (I do not test mac because I do not have a mac). And quite a lot resources on the Internet also says that.