export_svg crops node labels

[alcooj]

Hi, Rich.

Thanks for creating this package.

Would it be possible to add an argument to export_svg to increment the svg width? Some of my node labels are longer than the node shape (by intention); it seems that the function only considers the nodes when it tries to figure out the size of the canvas. In effect, long labels on nodes near the image's borders get cropped.

My current workaround is to grab the svg xml text and manually edit the svg width in an svg editor prior to rendering.