output help markdown directly, instead of going through man
make help headings bright
prettify subcommand listing
partial cleanup of option listing
more cleanup of option listing
fix indentation for options
Make `wp` show the same output as `wp help`.
rename '_sys' to 'cli'
ignore first parameter to WP_CLI::add_man_dir()
remove man/ dir
Merge pull request #548 from wp-cli/inline-help