determining what does and doesn't get into the R-C extraction
output. Added option "debug" and moved all excess diagnostic
information to be gated by this flag. Corrected an issue in
the standard extraction in which the substrate is always output
with zero lumped resistance, preventing it from being checked
by "extresist" for inclusion or exclusion in the .res.ext output.
Reinstated the computation of minimum resistance transistor but
excluded other devices. Added more sane handling of exceptional
conditions like loops. The result is a more consistent check of
nets in the design. However, I still need to recheck the
"rg_maxres" calculation because it appears to be too low.