This adds completion files for zsh that cover most of notmuch's cli.
The files in completion/zsh are formatted so that they can be found by
zsh's completion system if put $fpath. They are also registered to the
notmuch-* pattern, so they can be called externally using _dispatch.
Update installation recipe and drop debian/notmuch.examples to avoid
breakage. This means zsh completion is not installed for debian, to be
fixed in a future commit.
Amended by db: use regexp searching for address completion. This seems
to be fast enough to work without a cache.
The original "contrib" name is lousy. Everything in notmuch has been
contributed, and we are integrating as much of it as possible, (rather
than making users grub through contrib looking for useful pieces to
install).
Meanwhile, the only things we have in contrib are command-line
completion scripts, so "completion" makes more sense as a name, (and
helps make "./configure" slightly less ambiguous).
