FlightGear - Flight Simulator FGAddon

Initial import of 777

Mosquito: add propeller pitch levers to the cockpit.

* Models/Instruments/boost-[ps].xml,
Models/Instruments/boost20/boost20-[01].xml: delete.
* Models/Instruments/boost20/boost20.xml: take the boost pressure as a parameter.
* Models/cockpit.xml: load Models/Instruments/pitch.xml.
Pass the boost pressure of each engine as a parameter to boost20.xml.

Mosquito: remove the gunsight from the bomber, keep it only in the fighter-bomber.

Mosquito B mk XVI: remove one redundant pair of propellers from the model.

Lockheed1049h: normalize all property names *not* to start with a slash.

Thanks to Emilian for the explanation.
Closes: https://sourceforge.net/p/flightgear/tickets/4/

Lockheed1049h: repair animations over multiplayer

Thanks to Emilian for reporting the bug so quickly and for the
detailed explanation.
Closes: https://sourceforge.net/p/flightgear/tickets/4/

Mosquito:
* Bug fix: make the cockpit instruments appear in the bomber variant.
* Bug fix: make the RPM indicator needles rotate correctly.
* Models/Instruments/ignition-gb/ignition[12].xml: factorize into ignition.xml.
* Models/Instruments/rpm-[ps].xml: factorize into rpm.xml.
* mosquito-common.xml: new; factorize most of the mosquito model.
Do not start with engines running; }}s works.
Add a rating.
* mosquito-fbVI-set.xml, mosquito-set.xml: include the above.
* Models/cockpit.xml: bug fix: relocate the beam_approach instrument to make
it visible.
* Models/Instruments/rpm5k-gb/*: delete, redundant with rpm.*

mosquito:
* Make all paths relative.
* Normalize the indentation of all XML files.

Lockheed1049h: revert the part of the previous commit inside <aerodynamics>

It seems JSBSim does not in fact support property names starting with a slash.

Lockheed1049h: normalize property names always to start with a slash.