Reverted ambigious change from editable's bootstrap code.
Fixed code-style in DTD.
Call editor#attachToForm only if editor#element has form.
Various changes to editor#readOnly flag.

* Improved editor#readOnly discovery to consider inline-textarea.
* Changed disabled attribute check from getAttribute to hasAttribute since disabled has no value.
Fixed editor#updateElement doc string.
Re-factored various changes in the inline creator.

* Reverted: Ambigious readOnly fix (now handled by editor itself).
* Reverted: Conditional setData (broken startup event chain by not calling setData event)
* Simplified inline container invokation.
* Fixed initial data set-up (textarea.getValue but nontextarea.getHtml).
* Attach to form only when form is present.
* Improved destroy listener to modify container only when inline-textarea.