Added a few 'internal' features for the optimizations.
New preprocessor variables optimvalue_ and optimscheme_
The experiments=number option (active when O3)
   number=0  The regular mcts search
   number=1  mcts search with linearly declining C_P
   number=2  mcts search with in the first half linearly declining C_P
             in the second half C_P = 0.01 times the original C_P.
   number=3  each search has a 50% chance to have the original C_P
             and 50% chance to have C_P = 0.01 times the original C_P.
In addition the scheme=(...) option can read dollar variables.