Postupdate is now working again (#5512)

Postupdate is now working again (#5512)

* "post-type" replaces "bookmark" and "type"

* Removed some more type

* Added index to permission set

* The permission set is now stored

* The permission set is now removed upon expiry

* Post update now stores the permission set

* New file

* Permissions are now sorted

* The permission set is now used for item permissions

* Check for allow_cid, ... is superfluous. Checking for "private" is enough

* We query the permissionset

* Permissions are displayed correctly

* Changed index

* We don't store the permissions in the item table anymore

* Permission fields are now deprecated

* Reversed ...

* Postupdate now handles "postopts" as well

* Set deprecated fields to "null" if empty

* Postupdates are enabled again