Conveyor upgrade system (#3912)

* conveyor/conduit upgrading system

* style

core/src/mindustry/world/blocks/distribution/ChainedBuilding.java

@@ -0,0 +1,7 @@
+package mindustry.world.blocks.distribution;
+
+import mindustry.gen.*;
+
+public interface ChainedBuilding{
+    Building next();
+}

core/src/mindustry/world/blocks/distribution/Conveyor.java

@@ -91,7 +91,7 @@ public class Conveyor extends Block implements Autotiler{
             Mathf.mod(req.tile().build.rotation - req.rotation, 2) == 1 ? Blocks.junction : this;
     }
 
-    public class ConveyorBuild extends Building{
+    public class ConveyorBuild extends Building implements ChainedBuilding{
         //parallel array data
         public Item[] ids = new Item[capacity];
         public float[] xs = new float[capacity];
@@ -391,5 +391,11 @@ public class Conveyor extends Block implements Autotiler{
 
             len--;
         }
+
+        @Nullable
+        @Override
+        public Building next(){
+            return nextc;
+        }
     }
 }

core/src/mindustry/world/blocks/liquid/Conduit.java

@@ -16,6 +16,7 @@ import mindustry.graphics.*;
 import mindustry.type.*;
 import mindustry.world.*;
 import mindustry.world.blocks.*;
+import mindustry.world.blocks.distribution.*;
 
 import static mindustry.Vars.*;
 
@@ -73,7 +74,7 @@ public class Conduit extends LiquidBlock implements Autotiler{
         return new TextureRegion[]{Core.atlas.find("conduit-bottom"), topRegions[0]};
     }
 
-    public class ConduitBuild extends LiquidBuild{
+    public class ConduitBuild extends LiquidBuild implements ChainedBuilding{
         public float smoothLiquid;
         public int blendbits, xscl, yscl, blending;
 
@@ -137,5 +138,15 @@ public class Conduit extends LiquidBlock implements Autotiler{
                 sleep();
             }
         }
+
+        @Nullable
+        @Override
+        public Building next(){
+            Tile next = tile.nearby(rotation);
+            if(next != null && next.build instanceof ConduitBuild){
+                return next.build;
+            }
+            return null;
+        }
     }
 }