These pieces are really hard to work with and sometimes the random
function will choose 3 of them at a time.

When we have two long boyes next to each other, they were looking
like one giant long boye.

Choosing a piece that can't be placed shouldn't automatically end
the game, since other pieces on deck might be able to clear a row or
column that this piece can then fit in.

Also reset the game.{x,y} when move_to_clear() fails so the piece
isn't hanging off the edge of the board.