Editable#setup called twice during wysiwygarea initialization

[Piotrek Koszuliński]

It is first time called in editable's constructor, second in onDomReady inside wysiwygarea plugin.

This may not be a wrong behaviour, though it looks like one. We should investigate whether after the first call every changes (new listeners, etc) are cleaned up before second call. This maybe happen thanks to clean up done by setData which is done in onLoad function inside 'wysiwyg' mode (not class) constructor.

If everything is ok, appropriate docs should be written to avoid confusion in the future. Why editable#setup has to be called for the first time and why for the second time?