Fix xplane plugin header includes

* Include only what is used
* Use forward declaration when possible
* Sorted includes

refs #598

src/plugins/simulator/xplane/xbusweatherproxy.h

@@ -7,13 +7,18 @@
  * contained in the LICENSE file.
  */
 
+//! \file
+
 #ifndef BLACKSIMPLUGIN_XBUS_WEATHER_PROXY_H
 #define BLACKSIMPLUGIN_XBUS_WEATHER_PROXY_H
 
-//! \file
-
 #include "blackmisc/genericdbusinterface.h"
 
+#include <QObject>
+#include <QString>
+
+class QDBusConnection;
+
 //! \cond PRIVATE
 #define XBUS_WEATHER_INTERFACENAME "org.swift_project.xbus.weather"
 #define XBUS_WEATHER_OBJECTPATH "/xbus/weather"