Just print a detailed path on the screen

Property definitions

ai $ SearchNode :: dump
	# Just print a detailed path on the screen
	fun dump
	do
		print "result:{state}"
		for n in path do
			var a = n.action
			if a != null then print "    + {a}"
			print "  {n.steps}: {n.state} ({n.cost}$)"
		end
	end
lib/ai/search.nit:728,2--737,4