Print the grid

Property definitions

ai $ PuzzleProblem :: print_state
	# Print the grid
	fun print_state(state: Array[Tile])
	do
		for i in [0..state.length[ do
			var t = state[i]
			if t == hole then
				printn "."
			else
				printn t.symbol
			end
			if (i+1) % width == 0 then print ""
		end
	end
lib/ai/examples/puzzle.nit:169,2--181,4