Shows how to drive an external program from DataTank.
You can use this to extend the functionality of DataTank, run convergence studies,
or as a test harness for code that will then move into a bigger code base.
This movie goes through how to create a Xcode project, how to set things up so
that Xcode will use inputs specified in DataTank, and how to modify the interface
between DataTank and your C++ program.