Chat mention color

+Chat mention / username color can now be set via hex in the settings
+ Users can invert the color of the mention text black/white
+ if an invalid color is provided, the default will be used

cockatrice/src/dlg_settings.h

@@ -162,8 +162,11 @@ private:
     QAction *aRemove;
     QCheckBox chatMentionCheckBox;
     QCheckBox ignoreUnregUsersMainChat;
+    QCheckBox invertMentionForeground;
     QGroupBox *chatGroupBox;
     QGroupBox *messageShortcuts;
+    QLineEdit *mentionColor;
+    QLabel mentionColorLabel;
 
     void storeSettings();
 };