If the address matching function generates no matches, don't prompt
the user to choose between them (!). Instead, generate a message to
report that there were no matches.
When completing an address, tell the user how many addresses in the
database matched the query.
Edited-by: Carl Worth <cworth@cworth.org>: Removed a stray numeric
literal that was causing a compiler warning.
A tool `notmuch-addresses' is required to produce addresses which
match a query string. An example of a suitable script can be found in
the git repository at
http://jkr.acm.jhu.edu/git/notmuch_addresses.git
There are no doubt others.
