Converts the collection to a .svg file and returns the data URL that describes the contents of the file.
var shape = Pablo.circle({r:50});
alert(shape.dataUrl());
An .svg file must include a root <svg> element. If the collection does not contain a single <svg> element, its elements are cloned, appended to a new <svg> element and the <svg> element is cropped to fit the contents before the data URL is created.