[orx-fcurve] Add FCurve.start, Fcurve.end, MultiFCurve.start, MultiFCurve.end

orx-fcurve/src/commonMain/kotlin/FCurve.kt

@@ -129,6 +129,31 @@ data class FCurve(val segments: List<Segment2D>) {
      * The unitless duration of the Fcurve
      */
     val duration: Double
+        get() {
+            return if (segments.isEmpty()) {
+                0.0
+            } else {
+                end - start
+            }
+        }
+
+    /**
+     * The unitless start position of the Fcurve
+     */
+    val start: Double
+        get() {
+            return if (segments.isEmpty()) {
+                0.0
+            } else {
+                segments.first().start.x
+
+        }
+    }
+
+    /**
+     * The unitless end position of the Fcurve
+     */
+    val end: Double
         get() {
             return if (segments.isEmpty()) {
                 0.0
@@ -137,6 +162,7 @@ data class FCurve(val segments: List<Segment2D>) {
             }
         }
 
+
     /**
      * Evaluate the Fcurve at [t]
      * @param segment an optional segment that can be used to speed up scanning for the relevant segment