gameboard setup on load
successful verification/exchange of moves

very unclean
added ply_breakout

helper function to turn notation into an object ready to be consumed by
the front-end
functional play

only for dwarf.  currently waits for dwarf move, then troll moves.

fixme: cannot move piece into previously occupied square
fixed bug: piece couldnt occupy vacated square

after leaving a square, the square was not emptied out, so further
pieces could not occupy it.  clearing out the square after successful
move fixes this