Changes to allow decoder height to be a 2x multiple of bitcell height.
Split of control logic tests.
Fixed track spacing in SRAM and channel router
PEP8 cleanup.
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.
Moved create_netlist and create_layout to the pgate class
from which everything is derived. Modified all pgates
to have consistent debug output and order of init function.