PenaltyTurbine will be similar to VelocityPenalty

So we'll start with a fork of that.  But the eventual changes are
going to be big enough (an additional SCALAR variable) to warrant a
new class IMHO.
Instantiate PenaltyTurbine when requested
PenaltyTurbine -> AveragedFan

For rotors with few blades the penalty formulation would probably have
been over-constraining; we're going to start by trying an averaged
lift/drag formulation.
AveragedFan residual contributions

Still need to put in Jacobians
Partial Jacobians for AveragedFan
AveragedFan jacobian bugfixes
Adding simple_fan example
Don't forget to generate new run.sh
Updated with new copyright
Fix div-by-zero bugs where no fan motion exists.
Add first attempt at simple_fan input
Merge pull request #136 from grinsfem/penalty_turbine

AveragedFan physics