public class MessagesImpl
This class implements the Messages interface.
This class serves two purposes. One is for backwards compatibility, it serves the old static API for accessing
messages. The other is a new API, which carries an inject messages, and a selected language.
The methods for looking up messages on the old API are called get, on the new API, they are called at. In Play 3.0,
when we remove the old API, we may alias the at methods to the get names.