Make ipfw's logging more dynamic. Now, log will use the default limit

  Make ipfw's logging more dynamic. Now, log will use the default limit
_or_ you may specify "log logamount number" to set logging specifically
the rule.
   In addition, "ipfw resetlog" has been added, which will reset the
logging counters on any/all rule(s). ipfw resetlog does not affect
the packet/byte counters (as ipfw reset does), and is the only "set"
command that can be run at securelevel >= 3.
   This should address complaints about not being able to set logging
amounts, not being able to restart logging at a high securelevel,
and not being able to just reset logging without resetting all of the
counters in a rule.