argparse-manpage v3

• New man page format: single-commands-section
• Add CLI and conf options for setting the output format
• Add CLI and conf options to explicitly specify %prog value
• Skip showing commands with help == SUPPRESS
• Avoid rendering docs for command aliases
• Print program name in upper case in header and footer
• The --author CLI option has changed, and takes arbitrary string
  (typically 'Author Name [email protected]'), and newly can be specified
  multiple times. Therefore, it now replaces the '--author-email' option.
  The --author-email option is kept, but is just an alias to the --author
  option.
• All CLI options can be specified also in setup.cfg
• Don't render AUTHORS and DISTRIBUTION if they would contain undefined values
• Remove '... was written by' from AUTHORS