refs #312, Navigator (aka navigation bars)

* different dyn. property names for main window, dock window and infoarea
* dyn.properties for nested QWidgets
* style sheet for navigator
* utility function to delete layout
* added standard OS icons, some formatting in CICons
* actions in main window to be used in navigator
* main window becomes normal window when minimized so it is correctly displayed in Win taskbar

Remark: Frameless floating dockwidgets with rounded borders not yet working

src/blackgui/qss/navigator.qss

@@ -0,0 +1,9 @@
+#fr_NavigatorDockWidgetInner[framelessDockWidget="true"] {
+  margin: 0px;
+  border: 2px solid green;
+  border-radius: 20px;
+}
+
+#fr_NavigatorDockWidgetInner QToolButton {
+  margin: 0px;
+}