- uncouple sector tag storage from the sector data to allow multiple tags per sector.

Tags are now handled by a tag manager class which stores sector/tag pairs. This way multiple entries can be added per sector.
Since UDMF does not have any arrays the additional tags are stored as a space separated string as 'MoreIDs'.

src/p_saveg.cpp

@@ -348,9 +348,13 @@ void P_SerializeWorld (FArchive &arc)
 		{
 			arc << sec->lightlevel;
 		}
-		arc << sec->special
-			<< sec->tag
-			<< sec->soundtraversed
+		arc << sec->special;
+		if (SaveVersion < 4523)
+		{
+			short tag;
+			arc << tag;
+		}
+		arc	<< sec->soundtraversed
 			<< sec->seqType
 			<< sec->friction
 			<< sec->movefactor