Add event to spline for updating custom data

Source/Engine/Level/Actors/Spline.cpp

@@ -416,6 +416,8 @@ void Spline::UpdateSpline()
         last.TangentIn = first.TangentIn;
         last.TangentOut = first.TangentOut;
     }
+
+    SplineUpdated();
 }
 
 void Spline::GetKeyframes(MonoArray* data)

Source/Engine/Level/Actors/Spline.h

@@ -348,6 +348,11 @@ public:
 
 public:
 
+    /// <summary>
+    /// Called when spline gets updated (eg. after curve modification).
+    /// </summary>
+    API_EVENT() Action SplineUpdated;
+
     /// <summary>
     /// Updates the spline after it was modified. Recreates the collision and/or any cached state that depends on the spline type.
     /// </summary>