New item field "Post-type" and new table "permissionset" (#5408)

* "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

* Changed documentation

src/Protocol/Feed.php

@@ -190,7 +190,6 @@ class Feed {
 		$header = [];
 		$header["uid"] = $importer["uid"];
 		$header["network"] = NETWORK_FEED;
-		$header["type"] = "remote";
 		$header["wall"] = 0;
 		$header["origin"] = 0;
 		$header["gravity"] = GRAVITY_PARENT;