Enhancement #180 - option to automate build prompts

[lilly-lizard]

(kinda) resolves #180

• adds --auto-build/-b option to automate rua promps for the upgrade, install and builddir subcommands
• doesn't add --noconfirm to pacman commands so user input is still required there. I think this is best because --noconfirm will actually select No when replacing another package which isn't the desired behavior for a -y option. However I'd be happy to add --noconfirm to the code if you'd prefer.
• automates build promps:
  • confirm install [O] in show_install_summary()
  • confirm upgrade [O] in upgrade_real()
  • confirm pacman install [S] in ensure_packages_installed() but skips [X] if first attempt fails
  • merge upstream [M]/use package [O] in review_repo()
  • skip tarcheck [O] in tar_check_archive()
• whenever user input is automated, a message is printed to give the user immediate feedback that an option has been chosen and what the equivalent user input would be
  • the autobuild messages are italicized to distinguish from proceeding output and reduce visual clutter
  • where appropriate the autobuild selection is colorized to match the preceding prompt