+JH/42 Internationalisation: change the default for downconversion in the smtp
+ transport to be "if needed". Previously it was "as previously set" for
+ the message, which usually meant "if needed" for message-submission but
+ "no" for everything else. However, MTAs have been seen using SMTPUTF8
+ even when the envelope addresses did not need it, resulting in forwarding
+ failures to non-supporting MTAs. A downconvert in such cases will be
+ a no-op on the addresses, merely dropping the use of SMTPUTF8 by the
+ transport. The change does mean that addresses needing conversion will
+ be converted when previously a delivery failure would occur.
+
+JH/43 Fix possible long line in DSN. Previously when a very long SMTP error
+ response was received it would be used unchecked in a fail-DSN, violating
+ standards on line-length limits. Truncate if needed.
+
+HS/01 Remove parameters of the link to www.open-spf.org. The linked form
+ doesn't work. (Additionally add a new main config option to configure the
+ spf_smtp_comment)
+