Always load preview when in preview mode, not in edit mode
Merge pull request #2091 from robert-h-curry/cms-preview-not-loading

Always load preview when in preview mode, not in edit mode
Replace DataObject->isNotNull() helper with closure

Now possible since we support PHP 5.3+ only.
TinyMCE "Insert Media" screen, update button triggers navigation (fixes #742)
Note about IE10 support
Removed "Last visited" from admin/myprofile (fixes #648)

It doesn't make any sense in this context
LeftAndMain.js: Fix 'X-Reload' for IE10 (fixes #647)
Min/max constraints for CMS dialog