Add "Crank" engine feature

v 1.1.3

The "Crank" position of the engine levers has no effect.

However ... from some videos it seems like a real world startup might have fairly long crank periods (for reasons unknown to me ... perhaps to reduce the stress on the turbine cludge because the rotors are already spinning) ... in the videos it can be seen that the rotors are spinning for a long time and then the white turbine smoke shows up. This seems to indicate that it was not the turbine which cause the spin in the initial phase.

It would be a nice addition to the get some manual crank (with some lower RPM limit of course .. not the full turbine speed)