Py3k:  compatible exception catching.
Normalize imports.
Py3k:  no tuples in arglists.
Py3k:  compatible imports for urllib-related stuff.
Py3k:  normalize StringIO.
Py3k:  compatible print in scripts.
Py3k:  moar StringIO normalization.
Py3k:  comaptilbe check for string types.
Py3k:  avoid 'unicode' keyword.
Py3k:  avoid 'long' keyword.
Py3k:  avoid mutating a dict while iterating.
Untangle unicode issues in dumper.
Fix tests on Python2 after StringIO switch.
Derived
Test on Python 3.2 / 3.3 using checkouts of ZODB/ZEO/hypatia.
Py3k:  mark bytes.
Py3k:  avoid bare unicode literals.
Py3k: Work out str/bytes for folder __getitem__ etc.
Py3k:  avoid filter() / map() generators.
Py3k: ensure we store 'mimetype' as unicode.