[5.14.1] UI adjustments

* OS native check of screen resolution (Qt free, experimental)
* changed rounding
* use string for scale factor so we can use fractions as 2/3
* utility functions to clean numbers, parse fractions

It looks like:

* my WIN10 scaling is 250%
* obviously swift rounds that to 3 (device ratio)
* now using FLOOR policy down-rounding to 2
* rational: scaling up (scale factor) is better as down-scaling as the factors would be clearer
* 2->3 1.5, but 3->2 means 0.66667

src/swiftdata/main.cpp

@@ -25,9 +25,9 @@ using namespace BlackGui;
 
 int main(int argc, char *argv[])
 {
-    CGuiApplication::highDpiScreenSupport(CGuiApplication::parseScaleFactor(argc, argv));
+    CGuiApplication::highDpiScreenSupport(CGuiApplication::scaleFactor(argc, argv));
     QApplication qa(argc, argv);
-    Q_UNUSED(qa);
+    Q_UNUSED(qa)
 
     CCrashHandler::instance()->init();
     CGuiApplication a(CApplicationInfo::swiftMappingTool(), CApplicationInfo::MappingTool, CIcons::swiftDatabase48());