Upstream changes for MIMEDefang 2.74:

• Increase buffer size for md-mx-ctrl responses.
• Close input file handle in append_to_html_part. Bug found by Kees Theunissen.
• Add action_add_entity function.
• Simplify code in action_replace_with_warning.
• Remove obsolete text from man page.
• Avoid deprecated "defined(@array)" construct.
• Implement new "load1" md-mx-ctrl command which gives statistics in more useful format than "load"
• get_mx_ip_addresses: Treat MX records of '', '.', '0', '0.', '0 .' and '0 ' as bogus.
• watch-multiple-mimedefangs.tcl: Major improvements; see the new -n, -r, -s and -t command-line options.
• Add rcpt_addr, rcpt_host and rcpt_mailer to default set of macros that we ask for.
• Log Sendmail queue ID in more places.
• Remove dead "connect_to_socket" routine in mimedefang.pl
• Do not invokve smfi_setsymlist unless "-y" option to mimedefang is given. smfi_setsymlist leaks memory in versions of Sendmail prior to 8.14.4.