CKEDITOR-104: better way of testing whether xwiki-events-bridge is missing and a safety to prevent recursive event firing

* Update version after releasing v1.8.3

This reverts commit bf907fd8.

* Put the SNAPSHOT version back after releasing v1.8.2

This reverts commit fe58c0bc.

-> Update version after releasing 1.8.1

This reverts commit 9b97d369.

* Take into account the attributes set from TextAreaClass (rows, cols, disabled)
* Use lowercase "wysiwyg" category
* Check if the syntax is supported and fall back on a plain text area

* Move the editor code from the document content to the "code" property of XWiki.EditorClass (in order to leave the document content for the editor description which is translatable)

* Introduce a Velocity macro to load the CKEditor (to be used by the edit sheet and the editor component)
* Fix the edit layout (e.g. add the title input) only when the edit sheet is applied
* Fix the modal z-index (the Export Page modal was displayed under the modal backdrop)
* Rename HTMLConverterMacros to VelocityMacros and add more generic macros
* Expose the CKEditor as an Editor<XDOM> using XWiki.EditorClass
* Use silent notation when generating the editor HTML

* Make sure we don't change the order of the form fields because this breaks Chrome's Back-Forward cache.

CKEDITOR-87: Table copy-pasted from a Word file into CKEditor does not display properly on page view
* Detect an empty line only when it's not the first or the last child node.

* Make sure we use the same code to render the content sheet when loading the CKEditor and when switching from Source to WYSIWYG.

* Add context menu entry to Open Link in New Tab