Various cherry picks from world thread safety

- Ensure monitor draw lists are not reused after deleting them.
 - Make terminal methods synchronized, avoding NPEs and IOOBEs when
   resizing.

src/main/java/dan200/computercraft/shared/peripheral/monitor/ClientMonitor.java

@@ -29,6 +29,7 @@ public class ClientMonitor extends ClientTerminal
         if( renderDisplayList != -1 )
         {
             ComputerCraft.deleteDisplayLists( renderDisplayList, 3 );
+            renderDisplayList = -1;
         }
     }
 }