[BioC] Rgraphviz load problem

[Jeff Gentry]

> installed what i think is the most current graphviz dmg for mac (1.10.dmg).

That's going to be the source of the problem, in SystemRequirements the
DESCRIPTION file specifies Graphviz >= 1.12 and you're using 1.10.  I'm
assuming a third party is building the dmg packages for Graphviz as that's
an absolutely *ancient* version of Graphviz.

This might be useful but I found this site:
http://www.pixelglow.com/graphviz/

But that also appears to be a really old version (1.13), but it is a lot
newer than 1.10.  Being a port I don't know how well it would integrate
wtih Rgraphviz however.

I'm not too familiar w/ the process in MacLand, unfortunately.