Enhances ands acp user clipboard

Enhances ands acp user clipboard

Changelog:

* Fixed illegal call `ClipboardHandler::getTypeID()` to `ClipboardHandler::getObjectTypeID()`
* Fixed wrong database table column name in `ClipboardHandler ::loadMarkedItems()`
* Removed unnecessary SID-related code in `ClipboardEditorItem::setURL()` since that is handled by the `LinkHandler`
* The urls of the clipboard editor items in `UserClipboardAction` are now properly set with the `LinkHandler`
* Fixes bug in `UserAction::validateDelete()` (`$this->users` instead of `$this->objects`)
* Fixes wrong way to get the action name in `ClipboardProxyAction`
* `WCF.ACP.User.List` now uses `WCF.System.Confirmation` for user deletion confirmation dialog.
* Added missing language items and renamed the two existing to better names.

TODO:
* After users are deleted, nothing happens. I think the best thing would be a page refresh.