Make it possible to display more than one editview at once.

Resolve a bug which nested divs after submitting changes

There were several things which made displaying more than one editview in
one page buggy up until now:
  * id's were used that were not unique across editviews
  * Due to this, the submit URL was not picked up properly
  * Due to this, messages might appear at unexpected places

After submitting a change through AJAX calls, you got one more level of
divs for this form. Though you did not really see this in your browser,
with these new changes this led to trouble.