[PATCH] lib: add 'body:' field, stop indexing headers twice.

[David Bremner]

David Bremner <david at tethera.net> writes:

> The new `body:` field (in Xapian terms) or prefix (in slightly
> sloppier notmuch) terms allows matching terms that occur only in the
> body.
>
> Unprefixed query terms should continue to match anywhere (header or
> body) in the message.

Last call for review. I'll push this change sometime in the next week
unless I am convinced otherwise.

d