De-listing

Not for merging yet.
We insert spacer brs between consecutive images/tables so that they're editable by users. You can see tests for this feature inside [blocking_elements.js](https://github.com/wymeditor/wymeditor/blob/master/src/test/unit/specific_feature_tests/blocking_elements.js). This is done by the `spaceBlockingElements()` call inside [fixBodyHtml](https://github.com/wymeditor/wymeditor/blob/master/src/wymeditor/editor/base.js#L979). I think there's currently a bug here where those br's will be removed and it won't be possible to put content between consecutive tables in the root of the document.

If you create test data with two consecutive tables at the root, you should be able to see the bug (although I can't remember in which browsers it appears). I think just calling `fixBodyHtml` as the last thing in this function should fix things.