More netcode updates

core/src/mindustry/net/Packet.java

@@ -10,6 +10,7 @@ public abstract class Packet{
     //readObject
     //readBuilding
     //readUnit (possibly)
+    protected static final byte[] NODATA = {};
     protected static final ReusableByteInStream BAIS = new ReusableByteInStream();
     protected static final Reads READ = new Reads(new DataInputStream(BAIS));
 
@@ -29,6 +30,8 @@ public abstract class Packet{
         read(read);
     }
 
+    public void handled(){}
+
     public int getPriority(){
         return priorityNormal;
     }