Initial Logbook read and write

xplugin/include/main.h

@@ -2,9 +2,12 @@
 #define GERMANAIRLINESVA_GACONNECTOR_XPLUGIN_MAIN_H
 
 #include "config.hpp"
+#include "constants.h"
+#include "logbook.h"
 #include "pathRecording.h"
 #include "simdata.h"
 #include "simulatorDatabase.hpp"
+#include "util.hpp"
 #include "websocket.h"
 
 #include "XPLM/XPLMDataAccess.h"