Eval

- bunch of code cleanup of various sorts
- change color scheme (both calc and eval)

![image](https://cloud.githubusercontent.com/assets/1767466/4801394/73a4ac56-5e32-11e4-992e-47468d706ca5.png)
![image](https://cloud.githubusercontent.com/assets/1767466/4801396/7aea7ce8-5e32-11e4-9dc8-c1c49cc4dccc.png)
- add new style dropdown block
- added quotes around string blocks

![image](https://cloud.githubusercontent.com/assets/1767466/4801417/cc10cba4-5e32-11e4-8cbc-9782c6e26b65.png)

- created some unit tests, and a util function for creating xml for some of these blocks
- added overlay block

- grunt test passes
I originally had it as functionalBlockXml, but my editor was getting confused with syntax highlighting. I'll maybe flip it to mathBlockXml