[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/swiftguistandard/swiftguistdinit.cpp

@@ -76,7 +76,8 @@ void SwiftGuiStd::init()
     sGui->initMainApplicationWidget(this);
 
     // experimental: avoid mic flickering
-    if (CBuildConfig::isLocalDeveloperDebugBuild()) { BlackSound::occupyAudioInputDevice(); }
+    // disabled for 5.14.1
+    // if (CBuildConfig::isLocalDeveloperDebugBuild()) { BlackSound::occupyAudioInputDevice(); }
 
     // log messages
     m_logSubscriber.changeSubscription(CLogPattern().withSeverityAtOrAbove(CStatusMessage::SeverityInfo));