Refactor qmake SUBDIRS structure

The big swift.pro is refactored by the correct usage of SUBDIRS
template. The following additional changes are made:
- Removed '_' from all targets and folder names
- Aligned parent folder and target name

refs #461

src/plugins/simulator/xplane/simulatorxplane.h

@@ -17,7 +17,7 @@
 #include "blackmisc/simulation/ownaircraftprovider.h"
 #include "blackmisc/simulation/aircraftmodellist.h"
 #include "blackmisc/pixmap.h"
-#include "plugins/simulator/xplane_config/simulatorxplaneconfig.h"
+#include "plugins/simulator/xplaneconfig/simulatorxplaneconfig.h"
 #include <QDBusConnection>
 
 class QDBusServiceWatcher;

src/plugins/simulator/xplane/xplane.pro

@@ -2,7 +2,7 @@ load(common_pre)
 
 QT       += core dbus network
 
-TARGET = simulator_xplane
+TARGET = simulatorxplane
 TEMPLATE = lib
 
 CONFIG += plugin shared