nodes: remove user input mutexes

These were no longer ever used and thus served no purpose.

app/node/node.h

@@ -248,12 +248,6 @@ public:
 
   virtual TimeRange InputTimeAdjustment(NodeInput* input, const TimeRange& input_time) const;
 
-  /**
-   * @brief User input lock prevents any user changes while a graph is being rendered
-   */
-  void LockUserInput();
-  void UnlockUserInput();
-
   /**
    * @brief Copies inputs from from Node to another including connections
    *
@@ -374,11 +368,6 @@ private:
 
   QList<NodeParam *> params_;
 
-  /**
-   * @brief Used for thread safety from main thread
-   */
-  QMutex user_input_lock_;
-
   /**
    * @brief Internal variable for whether this Node can be deleted or not
    */