ui: color schemes

Put all colors into single xml file. Accessing colors is handled via the singleton class ColorScheme. The default scheme
"bright.xml" holds the original colors. The scheme "dark.xml" is a start, but still a poor alternative. Color schemes
can be switched via the View menu.

src/lib/component/ComponentManager.cpp

@@ -60,6 +60,11 @@ void ComponentManager::refreshViews()
 			view->refreshView();
 		}
 	}
+
+	for (std::shared_ptr<CompositeView> view : m_compositeViews)
+	{
+		view->refreshView();
+	}
 }
 
 ComponentManager::ComponentManager()