[Cake] low bandwidth default params best effort vs voice latency.

[Dave Taht]

One thing the original sqm-scripts did (with fq_codel) was explicitly
deprioritize ping with a filter.

I had written  in my original "wondershaper must die" rant how stupid
it was to prioritize ping upwards  to "impress your friends" - as that
was the case in many, many a wshaper implementation I'd seen.

I only just now noticed that rant does not have the images inline.
"Oh, man, ping's prioritized:"

https://www.bufferbloat.net/projects/attachments/131229050304_wshaper-800-220.svg

As for explicit depriorization, well, I took a lot of flack from some
ietfers about lowering it below best effort, and I felt the additional
classification needed was excessive for cake, directly. Some OSes
already do mark it with a background class.  I still think it's a good
idea as it makes ping floods against (for example) your entire 10.
network (which happened to me under worm attack once) - vanish.