New Features

• passthrough $COLUMNS to allow header/separator to be scripted to have dynamic length
• improved readability by modularizing the code base

Bug Fixes

• fix misplacement of pasting texts in vi mode (fixed upstream in rustyline)
• fix $HOSTNAME not expanding in header
• nix integration (thanks to @staedoix)
• more portable contrib scripts (thanks to @Pebor)

Other

• minimal default config (let go of the capybara), that comes with a separator of dynamic length