Better Highlights (#1320)

* Support for user-defined sounds and colors

* Make color & sound columns selectable

* Add custom row for subscription highlights

* Add subscriptions to custom highlights and centrally manage highlight colors

* Dynamically update message highlight colors

src/messages/Message.hpp

@@ -55,6 +55,7 @@ struct Message : boost::noncopyable {
     QString displayName;
     QString localizedName;
     QString timeoutUser;
+    std::shared_ptr<QColor> highlightColor;
     uint32_t count = 1;
     std::vector<std::unique_ptr<MessageElement>> elements;