dummynet + CoDel, FQ-Codel, PIE, and FQ-PIE

[Don Lewis]

I'd like to see us get these patches committed to HEAD in time for
11.0-RELEASE: <http://caia.swin.edu.au/freebsd/aqm/downloads.html>

I've been running this stuff on my firewall box for a few months
and it has tamed the latency problems I was having with my DSL
connection to the internet whenever big uploads or downloads were in
progress.  Doing this with ALTQ would have been a lot more difficult
even if the CoDel stuff in ALTQ was documented ...