Label block

This replaces #362  and makes the text block a very simple label text block. 

It takes in a string, and a font size (in point values). 

It will:
* Rotate text with the sprite
* Move text to the end of the word
* Draws text at alphabetic baseline
* Always stamp LTR. There will need to be a bit of work done for RTL.

Example:
![screen shot 2014-06-29 at 10 22 34 am](https://cloud.githubusercontent.com/assets/1505907/3423921/a02170cc-ffb2-11e3-9d27-0bd111a033d5.png)

So, @cycomachead what happens if you have carriage returns and line breaks in the string? Granted, they're hard to write into the block's argument slot, but, you know, once we offer this people *will* try to print whole files with project Gutenberg books somewhere :-)
I guess you could either 1) do a lot and try to precisely handle multi-line text, or you could 2) only ever print the first line, or 3) filter out any new line characters and try to print everything.
Of course, everybody will want 1)
But I think 2) would be fine for me and for the purpose of this block (we *are* going to implement text boxes some time)