Back to 1 thread, since it seems to be about as fast as 4 or 8 and makes
benchmarking more consistent until I figure out concurrency issues.
Also change the default problem to involve more branching.
Remove a gratuitous cache.put, and comment out saving the cache to disk
while we're not using it.
Add some methods for identifying when hands have live flush draws.  Goal
is to prune the search tree when suits don't matter.  No noticeable
slowdown.

Also update to JUnit 4.
Rip out the multiple Scorer stuff.  Reduces time by ~30%.
Add a way to get the count of cards in a deck by rank.
Remove unused backRoyaltyMap code. 9% speedup.