Add orx-keyframer

orx-keyframer/src/demo/kotlin/DemoSimpleExpressions01.kt

@@ -0,0 +1,22 @@
+import org.openrndr.application
+import org.openrndr.extra.keyframer.Keyframer
+import org.openrndr.resourceUrl
+import java.net.URL
+
+fun main() = application {
+    program {
+        class Animation : Keyframer() {
+            val position by Vector2Channel(arrayOf("x", "y"))
+            val radius by DoubleChannel("x")
+        }
+
+        val animation = Animation()
+        animation.loadFromJson(URL(resourceUrl("/demo-simple-expressions-01.json")),
+                parameters = mapOf("cycleDuration" to 2.0))
+
+        extend {
+            animation(seconds)
+            drawer.circle(animation.position, animation.radius)
+        }
+    }
+}