Add a "--count-only" (or so?) option to "notmuch search" for returning
the count of search results.
+Add documented syntax for searching all threads/messages.
+
Give "notmuch restore" some progress indicator. Until we get the
Xapian bugs fixed that are making this operation slow, we really need
to let the user know that things are still moving.
from the user which changes are not interesting (such as the very
common mailing-list footer).
+Fix notmuch_query_count_messages to share code with
+notmuch_query_search_messages rather than duplicating code. (And
+consider renaming it as well.)
+
General
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Audit everything for dealing with out-of-memory (and drop xutil.c).