print-lib should preserve the root node attributes of svg documents

[ahocevar]

Depending on the SVG renderer of a map server, defaults may be added on the root node. Currently, print-lib only preserves version, width and height. This can result in incorrect output on the pdf document.

The attached patch fixes this issue by preserving all root node attributes in the xsl transformation.

Please review.

[elemoine]

it looks good to me, but I'd like to have Jesse take a quick look at the patch before commit. Jesse please commit the patch if it's ok to you.

Thanks for patch Andreas.

[elemoine]

r3419, patch from ahocevar, review from jeichar,