previously this was white+bold. the white aspect was dropped since this
would not be sensible for users with a white background for their terminal.
bold however does not have any effect for me at least so effectively there
is no highlighting at all.
here we reintroduce a colour, one that will work for both black and white
backgrounds of course. purple looks good to me - significantly different
to that used for errors and warnings, and works well with command
highlighting (as enabled separately).
346e3e1c36