Add dulwich.greenthreads module.
Remove pylint config.
Add 'flakes' target invoking pyflakes, and fix some pyflakes warnings.
Add pep8 make target and fix some pep8ness.
Add 'make before-push' target.
Stop using more deprecated test methods.
Use for loop instead of map.
NEWS entry for python3 changes.
index: Fix IndexEntry to not include name.