Merge pull request #9 from smathot/master

Looking good! I'll give 'em a test run as soon as possible (that is: when I can access the labs again, probably in the new year...).
proof of concept for docstring and baseclass inheritance in Display
added and tested BaseClasses and docstring copying for all core classes
Make fullscreen mode optional
Fix a bug where scaling was not taken into account in PyGameScreen.draw_image()
First pass at cleaning up the EyeLink code and reintroduce missing functionality relative to latest eyelink plug-ins
- The simple_tracker_experiment runs again
- Always save the camera image to a temporary file before showing
- Add calibration target beeps
- Add force_drift_correct option
Update to EyeLink functionality
- Saner drift-correction logic
- Migrate wouter's confirmation dialog from eyelink plug-in code