committing work-in-progress on new branch to rework architecture
continuing work-in-progress:
- refactored Stepper to take a generator for its sole argument
- fixed tests to work with this change
debugger.js creates tasks for running "draw" and "mouseClick" if they exists after it runs the main generator,
started writing tests for the debugger
start begins execution synchronously (everything else is async),
improved the debugger tests,
fixed an issue in the stepper that was caught by the debugger tests
updated the demo app to use the new debugger class