Log message:
py-orca: clean up

Log message:
devel/py-orca: Python library for task orchestration

Orca is a Python library for task orchestration. It's designed for
workflows like city simulation, where the data representing a model's
state is so large that it needs to be managed outside of the task
graph.  The building blocks of a workflow are "steps", Python
functions that can be assembled on the fly into linear or cyclical
pipelines. Steps typically interact with a central data store that
persists in memory while the pipeline runs.  Derived tables and
columns can be updated automatically as base data changes, and
pipeline components are evaluated lazily to reduce unnecessary
overhead.