Code:
- Rotation has a 'bump' at angle = 0.
- Try to get rid of relative imports.
- Join event server with event driver.

Tests:
- draw.py: pygame -> gtk + cairo.
- Nested widgets with rotation.
- Draggable shapes.

Report:
- Cited to VTK book, is this ok if I didn't read it?
- Normalize coordinates between (0.0, 0.0) and (1.0, 1.0)?
- Experiment met Processing-Python code port nog wel beschrijven of uberhaupt
  weglaten?
- Moet er nog een conclusie bij? En wat moet daar dan in staan?