fix: gracefully handle browsers that don't support svg elements

This PR detects browsers that don't handle SVG elements (IE8,9 AFAIK) and handles this situation by logging an error and creating elements without a namespace (in this case nothing will be shown in a browser). There are several sub-changes in this PR:
* the hsp/document.js is moved to hsp/rt/document.js as it is only used in the runtime
* there is a new hsp/rt/browser.js service that can be used to sniff browsers' features
* the mentioned sniffer is used in elnode.js to handle SVG elements gracefully in browsers without SVG support