int() is really now long() in py3k, but to avoid breaking 2.6/2.7, we leave
the integer types where they are and just map long to int in py3k.
Also, pretty proud of myself for finding an easy way of detecting py3k.
This is, I guess, a few things the Python devs were just fed up with.
* "while 1" is now "while True"
* Types are compared with isinstance instead of ==
* Sort a list in one go with sorted()
My own twist is to also replace type('') with str, type(()) with tuple,
type([]) with list, type(1) with int, and type(5000.0) with float.
What's really going on is that map() and filter() return iterators in py3k.
I've just gone ahead and turned them all into list comprehensions, because
I find them much easier to read.
y.has_key(x) is gone (use x in y), and keys(), values(), items(), and
range() all return views.
Some iterables needed to be packed into lists, either because the code
expected a list (such as "range(256) * 3") or because the original
collection was being modified (automatic global declarations).
The Tiff ImageFileDictionary is a special case and will be dealt with in
another commit.
