Added XYParameter demo, made XYPad draw it's label

orx-gui/src/demo/kotlin/DemoXYParameter.kt

@@ -0,0 +1,32 @@
+import org.openrndr.application
+import org.openrndr.extra.gui.GUI
+import org.openrndr.extra.parameters.ActionParameter
+import org.openrndr.extra.parameters.Description
+import org.openrndr.extra.parameters.XYParameter
+import org.openrndr.math.Vector2
+
+fun main() = application {
+    configure {
+        width = 800
+        height = 800
+    }
+
+    program {
+        val gui = GUI()
+
+        val settings = @Description("Vector parameter!") object {
+            @XYParameter("Position", 0.0, 800.0, 0.0, 800.0,
+                    precision = 2,
+                    invertY = true,
+                    showVector = true)
+            var position: Vector2 = Vector2(0.0,0.0)
+        }
+
+        gui.add(settings)
+
+        extend(gui)
+        extend {
+            drawer.circle(settings.position, 50.0)
+        }
+    }
+}

orx-gui/src/main/kotlin/Gui.kt

@@ -463,6 +463,7 @@ class GUI : Extension {
                     precision = parameter.precision!!
                     showVector = parameter.showVector!!
                     invertY = parameter.invertY!!
+                    label = parameter.label
 
                     events.valueChanged.listen {
                         setAndPersist(