Clean up setup.py
Add 0.2.0 release date to CHANGELOG
Fix path to test map in doctest
Rename ImageRegion.image to .parent

The new name is much more clear
Raise ValueError rather than assert for out-of-bounds ImageRegion.get_pixel
Image slicing now returns ImageRegions
Remove set_pixel from images

Images are immutable now. A better drawing API is forthcoming.
Proxy ImageRegion.trans to the parent image
Add tests for image regions