Include <errno.h> to be safe

My glibc pulls it in from those other headers, but I can't find
anything in the spec guaranteeing that.
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