Added jTile files that will allow us to integrate the
download-local-copy-of-the-map functionality into our existing GUI. I
haven't been able to resolve some of the dependency issues in the
jTile.src.org.openstreetmap.gui.jmapviewer directory; I believe that (at
least some) of the issues here stem from the fact that we have two
different jmapviewer implementations in this project, one under
org.openstreetmap.(etc) and one under jTile.src.org.openstreetmap.(etc),
and these two are not being properly distinguished.

Next steps for the GUI:
(1) Fix jTile dependency errors (those described above)
(2) Implement basic tabs in the GuiMain.java file in src.gui for (a)
command send / information receive (b) tracking with jmapviewer, and (c)
download local copies of certain areas of the map (which we will borrow
heavily from the now included jTileDownloader files). 
(3) Add jTileDownloader functionality to the appropriate tab.
(4) Optimize jmapviewer functionality in the appropriate tab (recovery).
(5) Modify LocalTileSource (and perhaps other related files) to read
from local copies of the map. (We should keep these files in the source
directory, but we should not push these over git due to their sheer
size. Our GUI should appropriately handle files that do not exist
(display a message saying that some tiles that have been requested do
not exist on the local machine, etc.)
(6) Work to integrate GPS data so that we can plot the location of the
rocket as it lands (using dummy data).
(7) Integration of the XBee API/GUI that will enable sending & receiving
actual data to & from the rocket. The jmapviewer tab and control/message
tabs should be updated accordingly. 

Gus' goals for Dec. 1 (end of Thanksgiving break): 
(1) - (4) completed, with progress made on (5).