add hidden option to have compiler generate diagnostics in more machine-readable form

Currently, the compiler generates messages that are fully (and appropriately) i18n. This makes it harder to write tests and other infrastructure that wants to know the nature of error (file, line, error/warn/note, i18n-key, i18n args)
without caring about the actual text of the message. The hidden option would cause javac to use an alternative simpler format for diagnostic messages.
###@###.### 10/12/04 17:48 GMT