relocating variable definitions in etc/src/
aling rule: e.g. use_XXX XXX_rules XXX_dir XXX_cache_dir
rename:
$recipient_limit -> $smtp_recipient_limit
$incoming_mail_dir -> $incoming_mail_cache_dir
$outgoing_mail_dir -> $outgoing_mail_cache_dir
$qmail_control_virtualdomains_file -> $qmail_virtualdomains_file
s/header_filter/article_header_filter/
s/header_rewrite/article_header_rewrite/
s/body_filter/article_body_filter/
s/subject_tag/article_subject_tag/
verify_XXX_* -> check_XXX
newly defined:
$use_digest_header_rewrite
removed:
$smtp_log_dir
$smtp_log_file