Mantichora

Changes from the previous release: ([diff](https://github.com/alphatwirl/mantichora/compare/v0.9.5...v0.9.6))
- cleaned code
- fixed a bug in which the logging level was not effective
- added a new class `ThreadingHub`

Changes from the previous release: ([diff](https://github.com/alphatwirl/mantichora/compare/v0.9.4...v0.9.5))
- updated `README.md`, `setup.py`

Changes from the previous release: ([diff](https://github.com/alphatwirl/mantichora/compare/v0.9.3...v0.9.4))
- updated `README.md`, docstrings
- cleaned up code

Changes from the previous release: ([diff](https://github.com/alphatwirl/mantichora/compare/v0.9.2...v0.9.3))
- added `receive_one()`, `receive_finished()`
- changed the behavior:
- `mantichora` no longer waits all tasks to finish at exit of the
`with` statement. It terminates all workers.
- updated required `atpbar` version from 0.9.7 to 1.0.2
- updated `README.md`, `MANIFEST.in`, `setup.py`, tests
- cleaned up code

Changes from the previous release: ([diff](https://github.com/alphatwirl/mantichora/compare/v0.9.1...v0.9.2))
- updated `README.md`

Changes from the previous release: ([diff](https://github.com/alphatwirl/mantichora/compare/v0.9.0...v0.9.1))
- updated the development status to Beta in `setup.py`
- updated `README.md`