third round of indexing all files

[David Bremner]

David Bremner <david at tethera.net> writes:

> It seems noticeably faster (on the order of 30-50% faster) and the
> code is quite a bit simpler to adapt the approach in [1] to only
> delete the terms we are going to re-add via indexing.
>
> This obsoletes the previous series at [2]. It still has all of the
> issues mentioned there UI-wise, and the question of the index options
> design probably needs more thought.
>

Some belated testing reveals this implimentation is pretty broken. It
probably won't eat your database, but that's only because I forgot to
add a call to _notmuch_message_sync. So I'd recommend passing on this
for now. The previous approach is probably OK, although I'm going to
bash at this fancier approach a bit to see if I can make it work.