Minor fixes for linux build

refs #36
- Fixed compiler error in context.cpp (is not used anymore, but was still annoying)
- GCC was complaining about the template definitons in blackgui. Removing typename fixed it.
- Fixed a bug in qmake. Unfortunately qmake mkspec was just linux-g++ (not linux-g++-64), so added this case.
- Fixed a PRE_TARGETDEPS bug
- QMake has strange behaviour with DBUS_ADAPTORS: include the header somewhere, otherwise it won't be generated.

refs #81

src/blackcore/dbus_dummy.cpp

@@ -0,0 +1,10 @@
+/*  Copyright (C) 2013 VATSIM Community / contributors
+ *  This Source Code Form is subject to the terms of the Mozilla Public
+ *  License, v. 2.0. If a copy of the MPL was not distributed with this
+ *  file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// These two header files are not really needed here. But if they are not
+// included "somewhere", they are not generated -> compiler error!
+// Possible solution: Generate them once and put them in git.
+#include "contextnetwork_adaptor.h"
+#include "contextsettings_adaptor.h"