FlightGear - Flight Simulator FGAddon

When engaging supercharger high speed, the manifold pressure would
drop while engine power would increase. This was unrealistic and has
bugged me for years :) This is now corrected.

* Engines/WrightCyclone-972TC18DA3.xml: adjust volumetric efficiency,
supercharger parameters. Introduce a fixed bsfc.
* Systems/engine-filters.xml: delete the filters computing a variable
bsfc.
* Help/help.xml: adjust the procedures accordingly.
* Lockheed1049h-common.xml: increment version number.
* Nasal/Lockheed1049h-fuel.nas: add a debugging aid computing
endurance and range remaining at current ground speed, results in
/consumables/fuel/endurance-remaining,
/consumables/fuel/range-remaining-nmi.