big changes in Container class and other

order of namespaces in args_aliases: it's important for setns! via sr…

…c of nsenter

add Inject class and cli

update Container, cli and docstrings with docs

additional argument 'all' in cli

change readme for pypi

add Chroot class and chroot option in cli

docs and argparse instead of click

pypi index and readme

fix readme for pypi