Firewall shuffling

Sepherosa Ziehau is planning to get rid of ipfilter.  It’s one of 3 firewall-ish programs in DragonFly right now, along with ipfw and pf.  Currently, pf is getting the most attention with Jan Lentfer’s porting work, though npf is also on the horizon.   However, ipfilter is currently in use at, so its removal may be on hold until it can be shown that ipfw or pf can stand in for it.  It looks like it will work out.