Xapian-quoting based batch tagging.

[David Bremner]

david at tethera.net writes:

> This is essentially just a rebase of 
>
>      id:1356464567-21779-1-git-send-email-david at tethera.net
>
> with some commit-message fixups for 
>
> [Patch v2 3/9] cli: add support for batch tagging operations to

pushed, with one blank line deleted, and one plural corrected, per Tomi
on IRC.

d