Fully implemented smell

-added locationGrid to the World class so that there is a common way to
access all of the locations without creating a new Location(row,col).
This was creating problems earlier with the contains() method in hash
maps and hash sets
-created a PriorityLocation class to be compatible with java.util's
PriorityQueue class
-updated the createWorldGraph() method to be recursive and account for
the direction being changed