Implement BGSCALE(2)

SMILEBASIC/bg.d

@@ -187,6 +187,11 @@ class BG
         this.scalex = x;
         this.scaley = y;
     }
+    void getScale(out double x, out double y)
+    {
+        x = this.scalex;
+        y = this.scaley;
+    }
     void rot(int rot)
     {
         this.r = rot;

SMILEBASIC/builtinfunctions.d

@@ -2378,6 +2378,14 @@ class BuiltinFunction
         }
         p.getBG(layer).scale(x, y);
     }
+    static void BGSCALE(PetitComputer p, int layer, out double x, out double y)
+    {
+        if (!p.isValidLayer(layer))
+        {
+            throw new OutOfRange("BGSCALE", 1);
+        }
+        p.getBG(layer).getScale(x, y);
+    }
     static void BGROT(PetitComputer p, int layer, int rot)
     {
         if (!p.isValidLayer(layer))