Increase some log entry levels from LOG_ERR to LOG_CRIT.
Changed spam.log entry for spam-bait messages from "REFUSED" to "IGNORED".
Added several statistics counters for connections/messages refused, ignored,
etc. and display the values when the mail server is terminated.
Handle lines of exactly MAX_LINE_LEN chars better in sockmimetext() - don't
add an extra blank line between lines.