Added optional ANSI color output for most errors

[Veltas]

Added new option -c for forcing colored output (at some point might be worth adding something to detect if in a colored term in interactive mode, to enable the automatically, for now you need to pass manually).

This colors type errors and warnings in a style very similar to the default colored output of GCC.

Colored output makes the errors/warnings easier to look through, and easier to pick out relevant information when trying to compile.

AFAIK it's just syntax errors I didn't add. I can make another PR for those later if people are in fact interested.

[Veltas]

Screenshot of colors in a normal terminal: http://i.imgur.com/KRvTFdY.jpg

[mascarenhas]

Thanks!