Provide an option to change the colors of text printed to the terminal

[mhucka]

The current colors used by IGA are hardwired. They are most readable on terminals with dark backgrounds, which is what I use, and are only so-so on terminals with light backgrounds. Worse, someone with visual impairments may have difficulty reading the text with its current color scheme.

IGA should either offer an option to skip coloring the text or offer to use a theme. The Rich theme manager may be helpful for this.