This fixes races in thread-local and global tagging in notmuch-search
(e.g., "+", "-", "a", "*", etc.). Previously, these would modify tags
of new messages that arrived after the search. Now they only operate
on the messages that were in the threads when the search was
performed. This prevents surprises like archiving messages that
arrived in a thread after the search results were shown.
This eliminates `notmuch-search-find-thread-id-region(-search)'
because these functions strongly encouraged racy usage.
This fixes the two broken tests added by the previous patch.
M-RET notmuch-show-open-or-close-all opens all closed messages.
The archiving change is mentioned twice, remove dupe.
"notmuch search" supports --format=text0 to work with xargs -0
The commands are long deprecated, so removal is probably overdue. The
real motivation is to simplify argument handling for notmuch so that
we can migrate to the common argument parsing framework.
