[cnmvmhvm] Chess position evaluations priority queue

The next iteration of chess opening play out will probably not play until end of game; instead, concentrate on just the opening phase.  Instead, it will explore a much wider set of openings.  Rough idea is that the outcome of the game is sometimes obvious when the middlegame rolls around, and computers of the future will easily be able to play out the remainder of the game.

Put the unevaluated positions in a priority queue.  Components to calculate priority: total weight of position using chess piece values, move number, distance from main line (number of calculated moves).