Copy AveragedFan->AveragedTurbine

There won't be too many additional changes, so this might deserve
better refactoring later, but for now we'll just keep the code that
looks correct untouched and see if we can use it to help verify the
new stuff.
Initialize turbine-specific variables
AveragedTurbine initial_speed parameter
Add an AveragedTurbine test.  This won't pass yet.

We're using the regression results from the AveragedFan test; shortly
we'll add 1e50 moment of inertia etc. to make sure the AveragedTurbine
should behave identically.
AveragedTurbine init_variables bugfix
Refactor Multiphysics system, add nonlocal_foo()

This is going to be necessary to get AveragedTurbine working, but it's
a nice code reduction too.

We could make these method pointers into template parameters instead
to make the generated code equivalent to the previous case, but this
code is already heavyweight enough that funky templating is not where
I'd start with optimization.
Compatibility with FEMSystem::nonlocal_stuff()

Physics might now be called upon for evaluations of SCALAR variable
terms that aren't on an element at all; in those cases there's no harm
in calling the nonlocal_stuff() method requested, but we do need to be
sure not to dereference the NULL element.
We can do initial_speed without a special var
Weaken Composite*Function assertions

We can set an initial condition for some variables while leaving it at
the default 0 for others.
Getting turbine fan_speed equation working
Remove debugging line
Add simple_prop example
Fix simple_prop example
Now inputting turbine torque, not power
Fix sign error, nonlocal_mass_residual bug
Regression results updated for bugfixes
Added print_scalars option
Print the DoF *coefficient*, not index...
Adding ScalarODE physics

Hopefully simple systems with analytic solutions will be better for
debugging the new SCALAR infrastructure.
Assorted ScalarODE fixes

Not working yet, but this is indeed much easier to debug