Changed Slot in RelayNode to ProxySlot;

Changed PullData and PushData from SlotExtension to ISlot;

Added BackTraceExecutableNode;

Removed IExecutable from RelayNode;

Sample/Runtime/Models/Nodes/BaseClasses/BackTraceExecutableNode.cs

@@ -0,0 +1,19 @@
+namespace Misaki.GraphView.Sample
+{
+    public abstract class BackTraceExecutableNode : ExecutableNode
+    {
+        protected override void OnPullData(ISlot input)
+        {
+            if (input.LinkedSlotDatas.Count == 0)
+            {
+                return;
+            }
+
+            var outputNode = GraphObject.GetNode(input.LinkedSlotDatas[0].nodeID);
+            if (outputNode is IExecutable executable)
+            {
+                executable.Execute();
+            }
+        }
+    }
+}