Moved Controller\Ajax into Controller\App and added an ACL for preview (renamed from markdown)
Changed AJAX URL to reflect the change to Controller\App and preview().
Changed hrefs of <a> used for the write/preview tabs to reference on the anchors defined by the very same <a>. This enforces the browser to stay at the textarea and not scroll to the top of the page.
Commented out the <span> generation for required textares as the * is not integrating very well with the new preview tabs. This should be readded where needed in the templates.
Changed all templates with textareas to use the new preview functionallity. Added 'required' * in <span> where needed. Unified the CSS styling for the textarea sizes to be more consistent.