Add optional QR-code overlay for orx-rabbit-control

* Optional QR-code overlay for orx-rabbit-control
* Animate the QR-code overlay
* Changed orx-rabbit-control to the new demo structure
* Changed orx-rabbit-control README.MD

orx-rabbit-control/src/demo/kotlin/DemoRabbitControlManualOverlay.kt

@@ -0,0 +1,45 @@
+import org.openrndr.KEY_HOME
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.extra.parameters.*
+
+
+fun main() = application {
+    configure {
+        width = 800
+        height = 800
+    }
+
+    program {
+        val rabbit = RabbitControlServer(showQRUntilClientConnects = false)
+
+        val settings = object {
+            @BooleanParameter("White on black")
+            var whiteOnBlack: Boolean = true
+        }
+
+        rabbit.add(settings)
+        extend(rabbit)
+
+        /**
+         * Example: only show the QR code when the [KEY_HOME] button is pressed
+         */
+        keyboard.keyDown.listen {
+            when (it.key) {
+                KEY_HOME -> rabbit.showQRCode = true
+            }
+        }
+
+        keyboard.keyUp.listen {
+            when (it.key) {
+                KEY_HOME -> rabbit.showQRCode = false
+            }
+        }
+
+        extend {
+            drawer.background(if (settings.whiteOnBlack) ColorRGBa.BLACK else ColorRGBa.WHITE)
+            drawer.fill = if (settings.whiteOnBlack) ColorRGBa.WHITE else ColorRGBa.BLACK
+            drawer.circle(drawer.bounds.center, 250.0)
+        }
+    }
+}