svg direct links not refreshed when source updated

[pmorch]

If a source points to a http hosted file and the file changes, a refresh of the browser when looking at the main user interface causes the updated file to be picked up, rerendered and the new visualization is shown.

But if one is looking at a direct svg link, then a refresh of the browser does not automatically cause a the new version to be picked up and rerendered. The old version is still shown.