Re: ps(1) bugs and problems

I thought about this more and the change I proposed in
https://reviews.freebsd.org/D41231 seems unnecessarily complicated,
regardless of which characters will be chosen to denote going up and
down the process tree. ps -D'^$' suggests there are possibly more
characters to use and maybe even some kind of DSL is available.

So a simpler option is to keep the new aspect of -d (that it traverses
the tree down, even if ps is given a list of PIDs) and add a -D that
would work the same, but the other direction.

Piotr