[Development] Updated high-DPI support for Qt 5.14

[Christoph Cullmann]

Hi,

actually, unrelated to how one can configure the stuff, at the moment,
I see still a lot of Qt internal rendering artifacts for fractional 
scaling.

See https://bugreports.qt.io/browse/QTBUG-66036

For some I made now hacky workarounds in KTextEditor, see 
https://bugs.kde.org/show_bug.cgi?id=390451

Some still remain for factors like 1.1 and text selections...

And one should think about if it is really a good idea to accept factors 
like 1.1
and not round them to some at least 1 / 2^x factor that doesn't lead to 
interesting
accumulating rounding errors. (in addition to the opt-out of fractional 
scaling at all)

Greetings
Christoph

-- 
Ignorance is bliss...
https://cullmann.io | https://kate-editor.org