Colorize context: highlight file name, line number and function name with different colors

I have done some investigation, it seems that current icecream and pygments architecture are incompatible with it.

1. everything is rendered first, then colorized with pygments, then a hack for legacy Windows support is executed, all within colorize.
2. If we annotate output with control codes, they are escaped by pygments.

Reengineering of icecream seems to be needed to handle this.