Timestamps look like Gulp's, with grey times inside white brackets.
Files have cyan filenames, yellow line and column numbers, and grey TS{####} errors. I wonder if those are actually useful for folks using the --pretty CLI: are they used for anything outside Visual Studio... Can we just get rid of them?

Re-uses compiler/program's color logic in compiler/watch. The relevant variables are now exported and marked `@internal`. Is there a preferred way of re-using this code in both those files?