Add Oudard's script for terminal colors

This is a combination of 6 commits from https://gist.github.com/christian-oudard/220521

Christian Oudard kindly permitted the use and modification of his
script under the terms of the GNU GPLv3.

These commits were, from oldest to newest:

d4302077d00202d2a995cd78f864d655c535568e [empty commit message]

1d64892e9d3fb503939efe3d1a42ed9d2329db1b [empty commit message]

22a0aee6ea736d26ff34e48bdda635982787a75b
Made code compatible with python 2.6.

16f5ee5e3c54653846445dbedd67d30f2328d5a3
Added in-between gray colors from the RGB cube to the grayscale test graphic.

7d6b78a095c7a4225b6ffee34beaf5b7ebbfd87e
Added color name constants for system colors.

4bbddcddb3baf8280626b6546207bf7843ef6b64
Added a function, format_color, to format a string with color information without printing it.
Add copyright and GPL license to term_colors
Update colored output to use term_colors
Merge branch 'feature/add-term-colors-script' into develop