Beginnings of making ColorDecoder thread safe. This does not solve
many of the problems because EntitySet is still public.
Upping the android ADK version to 10 so that we can use some of the
concurrent collections that were added.
Fixed the StepSolution so it shows "Solved!" instead of "n+1/n".
Changed the ColorDecoder API to hide the internals of the ids collection.
Changed ids to be a ConcurrentSkipListMap so we don't have to keep a
parallel sorted array that is always out of sync. This also is much safer
because the multiple threads are accessing the decoder at once. This is
still not fully thread safe because of some internals that are directly
accessible. More cleanup TODO.