* New: In designflow.surelog, support for the Synlig Surelog/UHDM plugin
for Yosys.
* Fix: In designflow.svase, remove the transient file "slang-args.txt".
* Change: In designflow.yosys, remove the direct SystemVerilog support
that is delegated to Surelog and just load the resulting UHDM.
Merge with yosysnp and automatically detect if we can load the
Python plugin or go through a script.
* New: In cumulus.designflow: add yosysnp to manage Yosys without
Python support enabled.
Add klayout support for running scripts in batch mode.
Add generic system command support.
* Change: In cumulus.designflow.task.TaskFlow, systematically
convert pathes (str) into pathlib.Path in targets and depends.
* New: In cumulus.designflow.clean.Clean, add cleaning by glob.
Jean-Paul Chaput