Log message:
pkgdepgraph prints out a "dot" language specification of the
inter-dependencies of your installed packages.  The "dot" language
is interpreted by the graphviz package to make graphs.  There are
several uses for such information.

(1) A graphical representation of information is always good to
look at.

(2) The output itself can be sorted and filtered to provide a list
of packages to delete in order that they can be rebuilt (to replace
out-of-date components).

(3) You can visually estimate the work involved in (or impact of)
removing a given component in order to replace it.