ludorum.js v0.2.0

• Added Game.next() argument to control if the game state returned is a new state (as before) or the same state modified. This can be a big optimization for MCTS algorithms.
• Reworked aleatories (dice, distribution functions and CustomAleatory).
• Heuristic players now support contingent game states, except for MaxNPlayer.
• Added Puzzle15 as an example of a puzzle (singleplayer).
• Minor code cleaning and optimization.