ui: load project via MenuBar

This change adds a MenuBar to QtMainWindow and adds an action for opening a different project settings XML file. The
message MessageLoadProject is thereon used to load a new project in the Application and clearing the Storage.

src/lib/utility/messaging/type/MessageLoadProject.h

@@ -0,0 +1,22 @@
+#ifndef MESSAGE_LOAD_PROJECT_H
+#define MESSAGE_LOAD_PROJECT_H
+
+#include "utility/messaging/Message.h"
+
+class MessageLoadProject: public Message<MessageLoadProject>
+{
+public:
+	MessageLoadProject(const std::string& filePath)
+		: projectSettingsFilePath(filePath)
+	{
+	}
+
+	static const std::string getStaticType()
+	{
+		return "MessageLoadProject";
+	}
+
+	const std::string projectSettingsFilePath;
+};
+
+#endif // MESSAGE_LOAD_PROJECT_H