Added simulation files.

simulation/README.md

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+This is a simple example of a pluggable object simulator.  If you run the
+SimulatorRunner file, it'll throw up a GUI file picker if a simulation class
+isn't specified on the command line.  It will then:
+
+* Run the simulation class's `start()` method,
+* Call its `tick()` method,
+* Call its `use()` method,
+* then call its `stop()` method once `tick()` returns false.