Added ANSIString class. Allows a user to work with ANSI-encoded strings

Woo! Our first merge request on Github.

So! This is the ANSIString class. It should remove a lot of the problems with things like Prettytable and other pieces of code that need to know how long a string is, etc, and which were getting hung up on the ANSI color codes.

Griatch, this merge request will update with new commits if I add them, as it's linked to the master on both branches. You can comment on specific code sections if you have issues you need me to address.