Fix make test_all_confs (#3599)

* Hide 'no-overloaded-virtual' warnings inside JSBSim itself
* Cleanup link to non-existing
* Cleanup old airframes
* Fix: might be used uninitialized
* Fix MAVLink
* Cleanup
* DSDL compile error: new empy does not accept @)

conf/modules/fdm_jsbsim.xml

@@ -41,6 +41,8 @@
       $(TARGET).LDFLAGS += -L$(JSBSIM_LIB) -lJSBSim
       $(TARGET).CFLAGS  += -DNPS_JSBSIM_USE_SGPATH=$(JSBSIM_USE_SGPATH)
       endif
+      # Hide warnings from JSBSim itself
+      $(TARGET).CFLAGS += -isystem $(JSBSIM_ROOT)/include/JSBSim
     </raw>
     <file name="nps_fdm_jsbsim.cpp" dir="nps"/>
   </makefile>