Adding prototype of dialog system

This pull request implements an (almost) fully functional dialog system. It includes:

* A dialog catalog file, containing all speaker images, backgrounds and text to be rendered for the map. As such, it turns out we don't really need an entity to spawn the speaker images. I think the way I have it now is essentially as efficient as what we discussed. 

* Adding a new modal for a character. I realize now that there is no method for flipping images...only for animations. The easiest way to flip all other images is to just flip all the other character mugshots (except for the main character, since he will always be on the speaker on the right, and anyone else will be on the left). This wouldn't affect anything, just that the mugshots inside of the character stat screens would be flipped. 

**Bugs**
* Currently, the text displays on top of each other. We need a way to draw a line of text, then clear it and draw the next line. I'm not sure how this will work right now.

Other than that, it's almost complete.