+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
+relative to the database path. (Otherwise, moving the database to a
+new directory will result in notmuch creating new timestamp documents
+and leaving stale ones behind.)
+
+Fix notmuch.c to use a DIR prefix for directory timestamps, (the idea
+being that it can then add other non-directory timestamps such as for
+noting how far back in the past mail has been indexed, and whether it
+needs to re-tag messages based on a theoretical "auto-tags"
+configuration file).
+