[xswiftbus] Plane View Menu

FSX/P3D have a nice feature to follow a remote aircraft with the camera.
X-Plane was missing this feature, since for X-Plane the remote aircrafts
are not known. However, from a plugin point of view, we know them and where
they are. So we can manually control the camera and provide a similar
feature.
This is still very simple. As soon as you move the mouse, the PoV angle will
change. In future updates, it should be change only while the right mouse
button is pressed.

src/xswiftbus/plugin.h

@@ -57,6 +57,7 @@ namespace XSwiftBus
         CMenu m_menu;
         CMenuItem m_startServerMenuItem;
         CMenuItem m_toggleMessageWindowMenuItem;
+        CMenu m_planeViewSubMenu;
 
         std::thread m_dbusThread;
         bool m_shouldStop = false;