In py3k, imports are absolute unless using the "from . import" syntax.
This commit also solves a recursive import between Image, ImageColor, and
ImagePalette by delay-importing ImagePalette in Image.
I'm not too keen on this commit because the syntax is ugly. I might go back
and prefer the prettier "from PIL import".
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.
