+New keymap to view/save parts; removed s/v/o/| part button bindings
+
+ The commands to view, save, and open MIME parts are now prefixed
+ with "." (". s" to save, ". v" to view, etc) and can be invoked with
+ point anywhere in a part, unlike the old commands, which were
+ restricted to part buttons. The old "s"/"v"/"o"/"|" commands on
+ part buttons have been removed since they clashed with other
+ bindings (notably "s" for search!) and could not be invoked when
+ there was no part button. The new, prefixed bindings appear in
+ show's help, so you no longer have to memorize them.
+
+Default part save directory is now `mm-default-directory`
+
+ Previously, notmuch offered to save parts and attachments to a mix
+ of `mm-default-directory`, `mailcap-download-directory`, and `~/`.
+ This has been standardized on `mm-default-directory`.
+
+Better handling of errors in search buffers
+
+ Instead of interleaving errors in search result buffers, search mode
+ now reports errors in the minibuffer.
+
+Faster search results
+
+ Communication between search mode and the notmuch CLI is now more
+ efficient because it uses the CLI's S-expression support. As a
+ result, search mode should now fill search buffers faster.
+