Always show defaults in click CLI apps

You can add show_default=True to any @click.option so that the --help message displays the defaults, but it seems like click has chosen not to include something as helpful as argparse’s ArgumentDefaultsHelpFormatter, which aways shows the default. I remember searching for this a bunch of years back, but I finally came across a satisfying patch:

import click
click.option = functools.partial(click.option, show_default=True)