[plt-scheme] Re: test-coverage and colorblindness

Note that my email was prompted by an email from a student:

> I have red-green color blindness and I can't see the color differences
> between the tested and untested lines. Until I read this email carefully, I
> thought that "syntactic test suite coverage" was just broken on my machine.
> 
> Can these colors be changed? I didn't see relevant options in a cursory look
> through Preferences.

~ Aleks