Fonts demos improvments

A few different changes:
1.  Resize so that all test fits within the visible figure
1.  Rather than hard code Script MT as the cursive font add it to the list of cursive fonts. 
1.  Add Humor Sans to fantasy fonts where it seems to belong to make it more likely to have a fantasy font available when building the docs. 
1.  Use enumerate rather than hard coded loop lengths.

Before:
![fonts_demo](https://cloud.githubusercontent.com/assets/548266/5058816/34db1426-6cf9-11e4-8c2c-eee8d9a0fefd.png)
After:
![fonts_demo 1](https://cloud.githubusercontent.com/assets/548266/5058817/46daae7a-6cf9-11e4-871b-92cf282a3967.png)