[Issue 19776] [internals] Support i18n in error messages

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19776

--- Comment #2 from Iain Buclaw <ibuclaw at gdcproject.org> ---
For future reference, keyword flags used to extract strings from dmd front-end.

--keyword=
--keyword=_
--keyword=error
--flag=error:2:c-format
--keyword=errorSupplemental
--flag=errorSupplemental:2:c-format
--keyword=warning
--flag=warning:2:c-format
--keyword=warningSupplemental
--flag=warningSupplemental:2:c-format
--keyword=deprecation
--flag=deprecation:2:c-format
--keyword=deprecationSupplemental
--flag=deprecationSupplemental:2:c-format
--keyword=message
--keyword=verror
--flag=verror:2:c-format
--keyword=verrorSupplemental
--flag=verrorSupplemental:2:c-format
--keyword=vwarning
--flag=vwarning:2:c-format
--keyword=vwarningSupplemental
--flag=vwarningSupplemental:2:c-format
--keyword=vdeprecation
--flag=vdeprecation:2:c-format
--keyword=vdeprecationSupplemental
--flag=vdeprecationSupplemental:2:c-format
--keyword=vmessage

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