Adding a tree map to UI

This adds a small map element to the TreeViewer in the upper right corner of the webpage. This is an implementation of the feature mentioned in Issue #17. 

Map's functionality:
1. The map window is draggable, so the user can move it out of their way.
2. The map includes a box to indicate the current view of the tree.
3. The map is clickable to move (or transition) the current view to another location on the tree.
4. The map updates itself when the tree force changes (waits until it settles to save time).

A couple things to think about:
- In the dynamics view of the tree, the map hangs until the force settles. I don't know of a way to get around this problem. 
- Should the user have the option to turn this off?
- The structure of the webpage is very ugly. I suggest the next (ASAP) step is to think about the webpage design before adding too many more features?