Initial Version of Text Stamping

Hey all, this is an initial version of a text stamping block... It lets you input a size, font and string, and it prints text to the stage from the center of the sprite.

The real credit goes to @seanscofield for the hard work!, and I've made some tweaks to what he sent me.

Anyway, I'd like some feedback on code + fixes / features etc. 

TODO:
* Should text color default to the current pen color? I think so... 
* I think there should be a "Fonts" Drop down menu. The question is, which fonts should I include? I was thinking: 1 each of: serif,  sans, monospace and something fun.
* @ddgarcia suggested that text should be rotated along the direction the sprite is facing. I agree, but haven't been able to get it to work. A call to `.rotate()` causes no text to appear. Any ideas?
* Should the stage support text stamping? I'm not sure it makes sense because the stage has no pen.
* Newlines aren't supported because `fillText` doesn't support them... I could try some work-arounds, but is this a problem? Newlines currently get converted to spaces automatically.