Alphatwirl

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.23.0...v0.23.1))
- updated `README.md`, using the full URLs for image files
- used `README.md` as the long description in `setup.py`

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.22.0...v0.23.0))
- promoted the sub-package `progressbar` to an independent package
[atpbar](https://github.com/alphatwirl/atpbar)
- added `atpbar` to the default user modules in `parallel`
- added `atpbar` to `install_requires` in `setup.py`
- updated `.travis.yml` to install `atpbar`
- the sub-package `progressbar`, still in `alphatwirl`, is deprecated.

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.21.2...v0.22.0))
- updated progress bars
- made them properly work for nested loops
- unnecessitated manual initialization of the progress monitor
- it starts automatically when the first time atpbar is used
- removed the progress monitor from `Parallel`
- removed
- a deprecated object: `EventBuilderConfig`
- the implementation of deprecated classes: `EventBuilder`,
`BEventBuilder`
- an unused class: `EventLoopProgressReportWriter`
- `build_progressMonitor_communicationChannel()`, the
implementation of which had been already removed
- updated the log message in '_deprecated()'
- updated requirements for docs (for readthedocs)
- used raw string for regex in `HTCondorJobSubmitter`
- cleaned code

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.21.1...v0.21.2))
- implemented `is_jupyter_notebook()`

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.21.0...v0.21.1))
- removed an unrecognized option (`step`) of `IntProgress`

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.20.3...v0.21.0))
- added progress bars for Jupyter Notebook
- replaced `multiprocessing` with `threading` for progress bars as
Jupyter Notebook doesn't let a fork to display progress bars
- added function `atpbar`, which initializes `Atpbar`
- used in `EventLoop` and `ReaderComposite`
- added iterable `Atpbar`, which wraps another iterable and reports
progress during iterations, inspired by tqdm
- added a link to a quick start tutorial on Jupyter Notebook
mybinder.org in README.md