Make it less of a cpu hog. Log that the file was written.
pep8 pass 1
Node structure ditched for simpler list of lists style system. Less code. However - incompatible with the old files.
Lines - a way to eliminate an artifact of the square rendering
Add converter for old files (Helena has one she wants to keep). Convert normal file to json in/out. No need for the complexity of a pickle.
Add tool that uses pil to generate subdiv tree from an image file.
Demo images and runs for the tool
Update test file