Pitt-Peters inflow model for non-axial flight

[davidoort]

Is your feature request related to a problem? Please describe.
The current method for non-axial flight only takes into account the lift asymmetry due to the advancing and retreating side. In reality, a pitch up moment of the rotor is caused due to the fact that the front of the rotor receives "clean" air.

For the Honours, this might not be super crucial, but for Flight Control at Talaria I think it is pretty important to capture this moment.

Describe the solution you'd like
I would try to couple it to the Leishman method and see if it converges. The Pitt-Peters function would be a correction of the calculated induced velocity (so it would be added right after getLambda_Leish)

Describe alternatives you've considered
The Castles model I think also takes into account this effect but is a lot harder to implement.