How to tell to bzr version of plugin?

[Martin Pool]

> I wanted to be able to depend on the structured data of version_info,
> and in the spirit of DRY, having string formatted versions in each
> plugin is redundant, and - noting how Martin changed the formatter in
> bzr in 0.91 - prone to skew. (BTW, what was that change for?)

Alexander sent a patch to do this, I believe so that the strings would
be slightly easier to parse by other programs looking at the --version
output.

-- 
Martin