[Development] Revisiting high-DPI configuration options

[Prav]

Heello, Everyone!

> Then again, our SVG support is embarrassingly poor,
Exactly!
For example if you set SVG icon for button and then scale the app with something like QT_SCALE_FACTOR=2 before running the app ... icon will be bluered like this is not SVG!
With QT_SCALE_FACTOR=1 icon looks fine.
But fonts looks sharp for both QT_SCALE_FACTOR=1 and =2. Strange?
(Qt 5.6.1, Windows).

SVG icons are not shown at all in static builds of Qt, but png icons are fine (both icons are taken from resorse file). Static and shred Qt 5.6.1 build were done with same config settings except of cause "static".
Strange too.
(Qt 5.6.1, Windows).