Visualize and edit machine translation derivations using raphaeljs.

Resources:
 * http://grokbase.com/p/gg/raphaeljs/135twn41fq/how-to-move-text-and-rect-together-using-raphaeljs
 * https://github.com/marmelab/Raphael.InlineTextEditing
 * http://raphaeljs.com/graffle.html