revised UI color system when showing nodes

Olive now has a set of colors that categories can be "assigned" to. The timeline also shares the same colors as the NodeView. Colors can be configured per node (aka per clip).

app/node/node.h

@@ -154,6 +154,29 @@ public:
    */
   virtual void Retranslate();
 
+  /**
+   * @brief Retrieve the color of this node
+   */
+  Color color() const;
+
+  /**
+   * @brief Same as color() but return a pretty gradient version
+   */
+  QLinearGradient gradient_color(qreal top, qreal bottom) const;
+
+  /**
+   * @brief Uses config and returns either color() for flat shading or gradient for gradient
+   */
+  QBrush brush(qreal top, qreal bottom) const;
+
+  /**
+   * @brief Sets the override color. Set to -1 for no override color.
+   */
+  void SetOverrideColor(int index)
+  {
+    override_color_ = index;
+  }
+
   /**
    * @brief Return a list of NodeParams
    */
@@ -485,6 +508,11 @@ private:
    */
   QString label_;
 
+  /**
+   * @brief -1 if the color should be based on the category, >=0 if the user has set a custom color
+   */
+  int override_color_;
+
 };
 
 template<class T>