Convert to use li layer in pgates.
Fix multifinger devices with li layers.
Simplify wordline driver input routing.
Fix power pin direction option update.
PEP8 cleanup
Changes to simplify metal preferred directions and pitches.
Split of control logic tests.
Convert metalN to mN.
Generalize helper constants in modules for
space, width, enclose, etc.
Use layer stacks whever possible.
Try to remove drc() calls in liu of helper constants.