WYSIWYG editor shouldn't reformat anything if no modification is done to the content

Here's a good test:

• Edit a page in Wiki mode. Save its content somewehre
• Switch to WYSIWYG mode
• Save the page
• Switch again to wiki mode and compare with previously saved content. If the content is different then it's a bug

This happens for example in the case of XWIKI-1357, where the following:

* Log-in to XWiki from eclipse.
{image:connect-to-server.png|228|305|link=yes}
* Ability to select spaces to import.

Is transformed into:

* Log-in to XWiki from eclipse.

{image:connect-to-server.png|228|305|link=yes}

* Ability to select spaces to import.