Uses tkinter (*) to allow displaying a large or infinite image built out of
"tiles":
- Mimic internet mapping applications in Python.
- Explore procedurally generated images.
Yes, I know, it's ugly (actually, okay on Windows; very ugly using Anaconda on linux),
and unfashionable. It's not exactly fun to write tkinter code.
But it's part of the Python standard library, and there is something
to be said for "it just works".