[PATCH] Derive version numbers from git

[Sebastian Spaeth]

On 2010-04-06, Michal Sojka wrote:
> I often have several versions of notmuch compiled and it would be very
> helpful to be able to distinguish between them. Git has a very nice
> feature to make intermediate numbering automatic and unambiguous so
> let's use it here.

But, there are people without git installed that download the release
tarball. So if this patch makes it, we need to replace this with a
static version number when baking a release tar.

Sebastian