- Change ReloadCommand to use the new setting functionality
- Check and construct the messages file in NewSetting
- Unrelated: change MessagesManager not to extend CustomConfiguration anymore
- Abstract Messages into two layers: the top layer 'Messages' is how Messages can be retrieved and sent as before. In the background, package-private, MessagesManager actually does the file read and worries about I/O while Messages takes care of higher-level things (such as joining two lines or checking the current language).