Support messages without a line associated with it

[epage]

I am creating a tool that needs to report messages on the file itself and not a specific range within the file. I'd like these messages to be consistent with my annotate-snippets messages but the API requires having source associated with it.

[Navoos]

I would love to see what I can do, can I still work on this PR?

[epage]

This should now be able to be handled by Origin.