Partial game trees

[sanskarchand]

We need capture and counting mechanics, and also the ability to try out some moves from any point in the game.

Leaving aside the algorithm for now, we need a data structure which keeps track of moves, and results.
Efficiency is paramount:

1. quick capture/count/endgame calculations
2. ability to efficiently store large partial game trees.

NOTE: generate full game tree at startup (for jumping to moves quickly and such)?
ADDENDUM: Something like gnugo's worms and dragons perhaps?