Log Message:
argparse 1.4.0
- make argparse behave for default args aka
  issue 12776, 11839: call argparse type function only once.
- move to github:ThomasWaldmann/argparse
- add TW as maintainer / give TW's email
- add some usecase to README, clarify issue tracking
- add a note to tox.ini about testing on dead snakes