Add method for saving and closing a record.
t3lib_frontendedit has methods for the common tcemain actions that are performed on a record (save, hide, new, etc) but saving and closing a record is missing.
When editing page content, saving and closing is identical to just saving. Page records are slightly different though. When a page record is saved, we want to reload the editing form again. When a page record is saved and closed, we don't have any content to display; instead we want to figure out what the new URL is (after a change of page title, etc) and redirect the browser to that URL.
The attached patch adds a doSaveAndClose() method that is just a wrapper around doSave() so that the actual content is saved correctly. Having this separate method allows the frontend editing views to properly handle the saving of page records.
(issue imported from #M11167)