[API] Add missing ImNodes::EditorContextGetPanning (#152)

* Add editorContextGetPanning to ImNodes binding

* make editorContextGetPanning call by reference

* Fix typo

imgui-binding/src/main/java/imgui/extension/imnodes/ImNodes.java

@@ -440,6 +440,11 @@ public final class ImNodes {
         ImNodes::EditorContextResetPanning(ImVec2(x, y));
     */
 
+    public static native void editorContextGetPanning(ImVec2 result); /*
+        ImVec2 dst = ImNodes::EditorContextGetPanning();
+        Jni::ImVec2Cpy(env, &dst, result);
+    */
+
     public static native void editorMoveToNode(int node); /*
         ImNodes::EditorContextMoveToNode(node);
     */