Moves main inline editor controls to be embedded in the page instead of in the iframe so that the status of the page can be made more clear.
Changes preview system to use a cookie to persistent the current preview to allow for navigation.
Changes content locking to allow for continued edits (save drafts) and previews.
Changes PageFilter to resolve invisible items off main object if in preview for scheduling.
Changes Directory.Static.findByPath to return an invisible item if there aren't any visible ones.
Fixes bad nested scrolling behavior in embedded grid content form.
Fixes NPE in Directory.Static#findByPath.
Fixes embedded grid form not to display abstract content types.
Adds expand/collapse ability to embedded grid content form.
Merge branch 'release/2.3'