logic: Show error message when license expired

* moved all license checking logic to LicenseChecker
* create LicenseChecker instance in app
* Notify MainView with MessageForceEnterLicense

src/lib_gui/qt/window/QtMainWindow.h

@@ -85,7 +85,7 @@ public:
 	void loadLayout();
 	void saveLayout();
 
-	void forceEnterLicense();
+	void forceEnterLicense(bool expired);
 
 protected:
 	bool event(QEvent* event);