#5 svg support for files without xml namespace

[Carlo Kok]

At the moment it's not possible to load svg files that
don't have the xmlns set. Although I know it's not 100%
valid, some tools use those, it would be great if the
following change could be added:

//SvgDocument class
public override XmlElement CreateElement(string prefix,
string localName, string ns)
{
if (ns == null || ns.Length == 0) ns =
"http://www.w3.org/2000/svg";