TinyMCE integration: TODO

* implement generic insertAsset usecase
* implement generic insertLink usecase
* make java usecase handler generic and share with other editors
* when done, move these generic usecases into the editors module
* fix wysiwyg: some of the css styles are not properly passed to the editor
content (font-size and font-family)
* add onunload handler to avoid data loss if the user accidentally clicks
on a link or closes the window (confirmation dialog like bxe)
* allow multiple resource types to be edited with different valid_elements
settings. (partly done)
* allow multiple editable areas.

DONE:

* fix table plugin (it inserts bogus attributes and uses   regardless
of the "entities" setting being "raw", which leads to errors as the nbsp
entity is not declared in cocoon). -- cleaned up in save callback