V2 of directory delete patches

[Tomi Ollila]

On Sat, Oct 10 2015, David Bremner <david at tethera.net> wrote:

> Changes since id:cover.1443213654.git.jani at nikula.org
>
>   - tidy commit messages
>   - update docs in lib/notmuch.h
>   - make an executive decision not to push _remove_directory into lib
>   for now; it can always be a new api layer later.
>   - unmark fixed tests
>   - wrap xapian calls in try/catch


Looks good to me. tests pass.

Tomi