new translation article about level set

	new file:   visualization/_posts/2013-12-24-level-set-method-explanation.md
	new file:   visualization/img/levelset/annealing-1.png
	new file:   visualization/img/levelset/annealing-2.png
	new file:   visualization/img/levelset/annealing-3.png
	new file:   visualization/img/levelset/circle-1.png
	new file:   visualization/img/levelset/circle-2.png
	new file:   visualization/img/levelset/circle-3.png
	new file:   visualization/img/levelset/form-1.png
	new file:   visualization/img/levelset/form-2.png
	new file:   visualization/img/levelset/form-3.png
	new file:   visualization/img/levelset/heart-1.png
	new file:   visualization/img/levelset/heart-2.png
	new file:   visualization/img/levelset/heart-3.png
	new file:   visualization/img/levelset/heart-gradient.png
	new file:   visualization/img/levelset/heart.png
	new file:   visualization/img/levelset/img1.png
	new file:   visualization/img/levelset/img21.png
	new file:   visualization/img/levelset/img31.png
	new file:   visualization/img/levelset/levelset-n-120.png
	new file:   visualization/img/levelset/levelset-n-50.png
	new file:   visualization/img/levelset/levelset-n-52.png
	new file:   visualization/img/levelset/levelset-n-90.png
	new file:   visualization/img/levelset/levelset-square.png
	new file:   visualization/img/levelset/motion.png
	new file:   visualization/img/levelset/phi-difference.png
	new file:   visualization/img/levelset/tracking-v-shape.png
	new file:   visualization/img/levelset/tracking-valley-n-0.png
	new file:   visualization/img/levelset/tracking-valley-n-50.png
	new file:   visualization/img/levelset/tracking.png