Fix uncaught error in board.swap()
Fix uncaught error in board.swap()

Somehow, the board.swap() function was not changing the orbs in
the demo Board instance. All the tests pass both ways.

I will look more closely at the tests for swap to make sure they
are certainly reliable, but this edit is what should be there, and
it works for the demo.

PlaytestersKitchen/match-three-js,Droogans/match-three-js,PlaytestersKitchen/match-three-js,Droogans/match-three-js,PlaytestersKitchen/match-three-js