Editor fixes

core/src/mindustry/entities/def/PayloadComp.java

@@ -0,0 +1,16 @@
+package mindustry.entities.def;
+
+import arc.util.ArcAnnotate.*;
+import mindustry.annotations.Annotations.*;
+import mindustry.world.blocks.payloads.*;
+
+/** An entity that holds a payload. */
+@Component
+abstract class PayloadComp{
+    //TODO multiple payloads?
+    @Nullable Payload payload;
+
+    boolean hasPayload(){
+        return payload != null;
+    }
+}