added local_macros.props file to contain environment variables like SDL_DIR
added files for controlling experiments. wip.
merged donny's newest
Added framework for running experiments.

Experiment class is a manager for individual runs of an experiment.
Options are passed via a JSON config file.

Scene class is an individual run which manages meshes and reacts to input.
Logic goes here.

Reworked the MouseKeyboardInterface class to better fit with paradigm used
by Experiment.  Other input types may need to run in their own thread.

TODO:
- add logging to Scene.
- more input types
- should we have a 'replay' input type?
Merged in upgrade of InputStatus to REAL CLASS.  Not sure why this was necessary.