Colours, tables, trees and progress rows for the terminal

Colours, tables, trees, panels, bars and progress rows for OCaml command-line tools. console prints styled text and widgets into the terminal's normal scrollback, shows the work a program runs as progress rows under that text and redraws only those rows. It never takes over the whole screen. The console.tty library decides colour and UTF-8 for the standard outputs from the terminal and the environment, with Unix alone. The console.text library makes untrusted text safe to print, and console.input is a line editor that does no I/O.