Add TFinIndMod to the AD tail fin model

[andrew-platt]

Is your feature request related to a problem? Please describe. The tail fin induction is not currently included in the AeroDyn tail fin model. This is likely leading to discrepancies between the current SWRT regression tests and their equivalent FAST7 cert-tests (#15 - 17).

This would be controlled by the TFinIndMod=1 option in the AD tail fin file.

Describe the solution you'd like Add the induction model for the tail fin.

Describe alternatives you've considered

Additional context I'm adding this issue so we don't forget about it.