Added basic functionality for image nodes
Added basic functionality for image nodes

Extended the drawNode function to include basic image drawing. Adjusted the height and width functions to accommodate natural image dimensions as well as those set with node.data.image.width etc.
kidylee/springy,tigerleapgorge/springy,tigerleapgorge/springy,pingjiang/springy,pingjiang/springy,dabobert/springy,shigeruNakajima/springy,drstarry/springy,shigeruNakajima/springy,dhotson/springy,dabobert/springy,kidylee/springy,dhotson/springy