-Fix to use the *last* Message-ID header if multiple such headers are
-encountered, (I noticed this is one thing that kept me from seeing the
-same message-ID values as sup).
-
-Add support for the user to specify custom headers to be indexed.
-
-Add support for automatic tagging of new messages based on particular
-search criteria, (likely using an InMemory database for the new
-messages).
-
-Fix notmuch.c to call add_timestamp/get_timestampt with path names