Fixed many multiplayer bugs

core/src/io/anuke/mindustry/game/Unlocks.java

@@ -19,14 +19,6 @@ public class Unlocks{
         Settings.setSerializer(ContentType.class, (stream, t) -> stream.writeInt(t.ordinal()), stream -> ContentType.values()[stream.readInt()]);
     }
 
-    /**Handles the event of content being used by either the player or some block.*/
-    public void handleContentUsed(UnlockableContent content){
-        if(world.getSector() != null){
-            world.getSector().currentMission().onContentUsed(content);
-        }
-        unlockContent(content);
-    }
-    
     /** Returns whether or not this piece of content is unlocked yet.*/
     public boolean isUnlocked(UnlockableContent content){
         return rootSet().isUnlocked(content) || currentSet().isUnlocked(content);