Transition from ALTQ to priorities and queues

The rules after transition are likely simpler. No more selection of algorithms (it's HFSC anyway).

For simple configurations, set prio is enough. No need for queues here:

altq on $ext_if priq bandwidth 100Kb queue { q_pri, q_def }
  queue q_pri priority 7
  queue q_def priority 1 priq(default)

pass out on $ext_if proto tcp from $ext_if queue (q_def, q_pri)
pass in on $ext_if proto tcp to $ext_if queue (q_def, q_pri)

becomes

match out on egress set prio (5, 6)

Note: Priorities are now always important. Keep in mind that the default is 3.

For actual bandwidth shaping, HFSC works behind the scenes.