logic: file associations for Mac and opening project files via Mac OS

* hide start screen when opening with project file
* added project icon file to bundle and file type association to plist
* listen for file open events from double click or drag and drop
* fixed crashes in window handling

src/lib/Application.h

@@ -48,6 +48,8 @@ private:
 	virtual void handleMessage(MessageRefresh* message);
 	virtual void handleMessage(MessageSaveProject* message);
 
+	void startMessagingAndScheduling();
+
 	void updateRecentProjects(const FilePath& projectSettingsFilePath);
 
 	std::shared_ptr<Project> m_project;