Revision tracking, round 2

[Gaute Hope]

Excerpts from David Bremner's message of April 6, 2015 0:59:
> There is lots to tidy up here, but the series has balooned to 12 patches since since Austin posted
>
>       id:1413181203-1676-1-git-send-email-aclements at csail.mit.edu
>
> So I figure I better post it to get some feedback.
>
> These are unmodified from Austin's post
>  [WIP2 01/12] lib: Only sync modified message documents
>  [WIP2 02/12] lib: Add per-message last modification tracking
>  [WIP2 07/12] lib: Add "lastmod:" queries for filtering by last
>
> This has two small bug fixes, a typo and an extra * removed.
>  [WIP2 03/12] lib: API to retrieve database revision and UUID
>
> Together, the next 5  patches implement output format 3
>  [WIP2 04/12] cli: add type introspection to sprinter type
>  [WIP2 05/12] cli: add two sprinter utility functions
>  [WIP2 06/12] cli/show: add extra element to structured output for
>  [WIP2 08/12] cli/show: add lastmod to structured output
>  [WIP2 09/12] cli/search: add  metadata element to structured output
>
> These two do a trivial convesion of parts of the emacs interface to use the new format:
>  [WIP2 10/12] emacs: convert notmuch-search to format-version 3
>  [WIP2 11/12] emacs: convert notmuch-tree to format-version 3
>
> Finally, add db-revision argument. I'm not sure about the name, but I
> went with what Austin had written.  This patch should probably be earlier in the sequence
>
>  [WIP2 12/12] cli: add global option "--db-revision"

I have been running your 'revision-tracking' branch from
git://pivot.cs.unb.ca/notmuch for a week now, with heavy usage of the
revision features (I used the old series before that). This has all
worked without problems so far, and performance seems to be good.

- gaute