Added unit decal system for mods/future units

core/src/mindustry/entities/units/UnitDecal.java

@@ -0,0 +1,25 @@
+package mindustry.entities.units;
+
+import arc.graphics.*;
+import mindustry.graphics.*;
+
+/** A sprite drawn in addition to the base unit sprites. */
+public class UnitDecal{
+    public String region = "error";
+    public float x, y, rotation;
+    public float layer = Layer.flyingUnit + 1f;
+    public float xScale = 1f, yScale = 1f;
+    public Color color = Color.white;
+
+    public UnitDecal(String region, float x, float y, float rotation, float layer, Color color){
+        this.region = region;
+        this.x = x;
+        this.y = y;
+        this.rotation = rotation;
+        this.layer = layer;
+        this.color = color;
+    }
+
+    public UnitDecal(){
+    }
+}