ensure objects are in the correct thread when loading

Since we load in a separate thread, when the QObject based objects are
instantiated, they're created with affinity to that separate thread. Now we
specifically ensure they are moved to the main thread after their creation.

app/node/param.h

@@ -230,10 +230,15 @@ public:
 
   virtual ~NodeParam() override;
 
+  struct SerializedConnection {
+    NodeInput* input;
+    quintptr output;
+  };
+
   /**
    * @brief Load function
    */
-  virtual void Load(QXmlStreamReader* reader) = 0;
+  virtual void Load(QXmlStreamReader* reader, QHash<quintptr, NodeOutput*>& param_ptrs, QList<SerializedConnection> &input_connections) = 0;
 
   /**
    * @brief Save function
@@ -379,8 +384,6 @@ signals:
   void EdgeRemoved(NodeEdgePtr edge);
 
 protected:
-  void SaveConnections(QXmlStreamWriter* writer) const;
-
   /**
    * @brief Internal list of edges
    */