Recursive-Best-First-Search available

Just finished an implementation of the Recursive-Best-First-Search from Figure 4.5 page 102 of AIMA. The implementation may be found in aima.search.informed.RecursiveBestFirstSearch along with an associated test case in aima.test.search.searches.RecursiveBestFirstSearchTest, which creates a test that mimics Figure 4.6 from page 103. This has also been added to the MapDemo. I think a Genetic Algorithm implementation is up next :-)