Small tweak to section editing- try to generate a section (toc-)anchor from the edite...

Small tweak to section editing- try to generate a section (toc-)anchor from the edited section
and append that anchor to the url redirected to, so just edited section is shown by default

Shortcomings:
* won't append a number to duplicate headlines on a page (result: will go to first header with that content)
* doesn't actually parse the headline, headlines with [\\['{<>] in them will just fall back to the old behaviour