Default 1 thread and no temp subdirectory.
Add skywater setup/hold golden data
Add CLI option for simulation threads (-m)
Add compatibility mode option and nomodcheck for ngspice to speed up sky130 model loading.
Make subdir when using default /tmp dir.
Pass num_threads so temp subdirs are created.
Add hard decoder gates (nand, inv, pnan)
Add conditions for routing using LI layer in s8.
Generalize bus layers for decoders.
Move custom cells to own directory.
Fixed via directions, etc.
Add 4x16 hierarchical decoder and test case