Improved context sensitive help

- create utilty function CGuiApplication::triggerShowHelp
- this function also uses "QWhatsThis::leaveWhatsThisMode" which solves the problem that the help was not properly called a 2nd time
- adjusted using classes

src/blackgui/guiapplication.h

@@ -26,6 +26,7 @@
 #include <QCommandLineOption>
 #include <QDialog>
 #include <QObject>
+#include <QEvent>
 #include <QPixmap>
 #include <QScopedPointer>
 #include <QString>
@@ -159,6 +160,9 @@ namespace BlackGui
         //! Show help page (online help), use QObject::objectName as 2nd level context
         void showHelp(const QObject *qObject) const;
 
+        //! Static version used with dialogs
+        static bool triggerShowHelp(const QWidget *widget, QEvent *event);
+
         //! Style sheet handling
         const CStyleSheetUtility &getStyleSheetUtility() const;