Colorize the output to make it easier to see correct/incorrect answers

[François Marier]

In order to make it easier to see whether an answer was correct or incorrect, we should print the following in green:

  Correct!

and the following in red:

  The correct answer was (...)

Ideally, we should detect whether or not the terminal supports colors before using any.

As an alternative to using colors, we could use *bold* for correct answers and *reverse video* for incorrect ones.

[François Marier (fmarier)]

A number of third-party Python modules are mentioned on https://stackoverflow.com/questions/287871/print-in-terminal-with-colors but it's also easy to do on most platforms without any external dependencies by using ANSI escape codes:

  https://en.wikipedia.org/wiki/ANSI_escape_code

Auto-detecting support for ANSI colors is pretty hard:

  https://stackoverflow.com/questions/7445658/how-to-detect-if-the-console-does-support-ansi-escape-codes-in-python

and so it may not be worth it.