refs #312 navigation bars, contributes also to #347

* allow to set/unset frameless mode in CDockWidget
* adjusted context menus
* adjusted style sheets
* ini settings for margins
* hidden info area to host floating widgets only visible when floating (allows to CDockInfoArea widgets)
* made some private slots non-virtual

src/blackgui/components/navigatordockwidget.cpp

@@ -7,7 +7,6 @@
  * contained in the LICENSE file.
  */
 
-
 #include "navigatordockwidget.h"
 #include "ui_navigatordockwidget.h"
 
@@ -18,7 +17,7 @@ namespace BlackGui
     namespace Components
     {
         CNavigatorDockWidget::CNavigatorDockWidget(QWidget *parent) :
-            CDockWidget(parent),
+            CDockWidgetInfoArea(parent),
             ui(new Ui::CNavigatorDockWidget)
         {
             ui->setupUi(this);