Initial pass at supporting namespaces, SVG

Update the simple-html-tokenizer to gain de-normalized tag and attribute strings (https://github.com/tildeio/simple-html-tokenizer/pull/10).

Pass the parent element into the createElement helper so the namespace can be fetched. Fetch the namespace from dom elements as they render. Add several svg elements to the void elements list.

This needs optimization and far more corner-case testing, but it does actually work. The most controversial aspect is dropping the normalization from the tokenizer, and trusting users to properly capitalize these attributes and elements themselves. We don't clean up `viewname