[orx-composition] reverse argument order in draw()

Add demos with comments

orx-composition/src/jvmDemo/kotlin/DemoCompositionDrawer03.kt

@@ -3,10 +3,22 @@ import org.openrndr.color.ColorRGBa
 import org.openrndr.extra.composition.ClipMode
 import org.openrndr.extra.composition.composition
 import org.openrndr.extra.composition.drawComposition
+import org.openrndr.extra.svg.saveToFile
+import java.io.File
 
+/**
+ * Draws a composition using 3 circles and `ClipMode.REVERSE_DIFFERENCE`.
+ *
+ * A println() demonstrates that the result contains 3 shapes:
+ * a complete circle, a moon-like shape, and a shape with two small black areas.
+ *
+ * One way to verify this is by saving the design as an SVG file and opening
+ * it in vector editing software.
+ *
+ */
 fun main() = application {
     program {
-        val cd = drawComposition {
+        val composition = drawComposition {
             fill = null
             clipMode = ClipMode.REVERSE_DIFFERENCE
 
@@ -17,9 +29,14 @@ fun main() = application {
             circle(width / 2.0, height / 2.0, 100.0)
         }
 
+        println(composition.findShapes().size)
+
+        // save svg to a File
+        //composition.saveToFile(File("/path/to/design.svg"))
+
         extend {
             drawer.clear(ColorRGBa.PINK)
-            drawer.composition(cd)
+            drawer.composition(composition)
         }
     }
 }