FlightGear - Flight Simulator FGAddon

* Lockheed1049h-set.xml: load mk-crashed.nas in an XML entity *not* named Lockheed1049h;
the entity in Lockheed1049h-common.xml already contains one and an include XML file
cannot add to it. This makes engine fire work again.
* Models/Instruments/master_fire.{ac,xml}: import changes from the Lake of Constance,
with minor changes to the names of the objects.
* Nasal/mk-crashed.nas: do not set engines on fire if no fuel flows to them, even if
they are too hot (i.e. they may be cooling down after a fire). Make the probability
of engine fire become a certainty above 650 degF if fuel flows into the engine.
* Models/Lockheed1049h.xml: simplify the condition for rotating the nose wheel.