0.16.1

Fixed

• The tests of the private file modes skip the mode check on Windows, where files have no Unix modes.
• Docs, help examples and the skill name the example profile personal, not ya, as tg does. A second
  mailbox in an example is work. No behaviour changes.
• docs/configuration.md says which flag answers ask: --allow-dangerous for drafts delete, --yes for
  every other change, and confirmation_required without a terminal or a flag.
• The sender domain cache and the sign-in records folder are private to you. domain-ages.json is written with
  mode 600 and the folder that holds sign-ins.json with mode 700, as every other private file of mail's.
• Every error and issue reason mail raises is in its registry, so mail commands info lists it and an agent can
  branch on it: mail.smtp-login-refused, mail.no-drafts, mail.draft-unknown, mail.gmail-objectid,
  mail.export-destination-exists, download.exists, mail.unreadable, mail.deletions-skipped,
  mail.rules-unreadable and mail.export-unreadable. A test keeps the list complete.
• The secret scan knows Google's OAuth access tokens, refresh tokens and client secrets.
• mail commands info says what rules remove, rules apply and rules import answer with, as every other
  command does: mail_rule_change, mail_rules_apply and mail_rule_import. The answers are unchanged.
• rules apply closes its connection to the mail server before it answers, and the tag commands hand the store
  to the run, so a timeout or a signal closes it too.