Qtwirl

Changs from the previous release: ([diff](https://github.com/alphatwirl/qtwirl/compare/v0.9.1...v0.9.2))
- fixed a bug where successive calls of `_expand_config()` shared `shared`
- started applying default to `table_cfg` and `selection_cfg`
- cleaned code
- updated tests

Changs from the previous release: ([diff](https://github.com/alphatwirl/qtwirl/compare/v0.9.0...v0.9.1))
- updated `.travis.yml`, `setup.py`
- updated README.md

Changs from the previous release: ([diff](https://github.com/alphatwirl/qtwirl/compare/v0.07.0...v0.9.0))
- updated `.travis.yml`, `MANIFEST.in`, `setup.py`

Changs from the previous release: ([diff](https://github.com/alphatwirl/qtwirl/compare/v0.06.0...v0.07.0))
- changed the default `quiet` to `False`

Changs from the previous release: ([diff](https://github.com/alphatwirl/qtwirl/compare/v0.05.0...v0.06.0))
- defined `expander.py` as a generic module, which can become an independent package in the future.
- improved internal structure