Add a --remove-dups flag which removes duplicate files from search and
thread results. Uses fdupes if installed. Otherwise it runs a size and
Digest::SHA scan on each file to detect duplicates.
Signed-off-by: Stefano Zacchiroli <zack@upsilon.cc>
When asked for interactive help, lookup notmuch-search-terms(7)
instead of notmuch(1). Syntax of notmuch queries used to be described
in the latter, but has recently been moved to the former.
Closes: #675073 (in the Debian BTS)