Add full_name method to Command
Add identity method to Command
Add basic Presenter class
Add command_header and command_presentation methods to Presenter
Add usage_presentation method to Presenter
Add options_presentation method to Presenter
Add description field to Command
Do not add the newline in command header when there is no description
Use Presenter to show command help
Rename subcommand to differ from command alias
Add names_and_aliases method to Command
Add summarize method to Command
Fix adding aliases to subcommands in parent
Fix options processing
Get rid of stringification in Command and Option
Add subcommands_presentation method to Presenter
Use as_string instead of stringification in options_presentation