Move the stuff that fixes the size, orientation & fonts of graphs to

the debugging functions that call "dot". These fixed settings have
various problems: for example, the fixed size that is set in the graph
traits classes is not appropriate for turning the dot file into a PNG,
and if TrueType font rendering is being used, the 'Courier' TrueType font
may not be installed. It seems easy enough to specify these things on the
command line, anyhow.

llvm-svn: 13366