to not rely upon SQLAlchemy test libs,
nosetests must be run from within
examples/versioning to get around setup.cfg
breaking it.
- Tweak to examples/versioning to pick the
correct foreign key in a multi-level
inheritance situation.
- added READMEs to all examples in each __init__.py and added to sphinx documentation
- added versioning example
- removed vertical/vertical.py, the dictlikes are more straightforward