images support

image embedding can be done with a new node type: { image: 'imagePath.png' }
width can be provided to scale image proportionally { image: 'path.jpg', width: 100 }
width and height can be specified to stretch image { image: 'path.jpg', width: 100, height: 50 }
fit can be provided to scale image proportionally and make sure it fits into the rectangle { image: 'path.jpg', fit: [100, 80] }