Alphatwirl

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.25.5...v0.30.0))
- started testing in Python 3.8
- stopped testing in Python 2.7
- updated `README.md`, `.travis.yml`, `setup.py`, unittest

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.25.4...v0.25.5))
- made it possible to override the executable of HTCondor jobs by
the option `dispatcher_options` of `build_parallel()`
- updated for [\36](https://github.com/alphatwirl/alphatwirl/issues/36)
- deprecated `CollectorComposite` and `EventDatasetReader` in `loop`
- added replacements with the same names in `datasetloop`
- removed the deprecated class `EventsInDatasetReader`
- reorganized modules in `loop`
- updated unittest

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.25.3...v0.25.4))
- deleted deprecated function `listToAlignedText()`
- made minor edits to follow pep 8
- updated unittest

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.25.2...v0.25.3))
- updated `.travis.yml`
- replaced the channel NLeSC with conda-forge
- added Python 3.7
- updated the versions of ROOT and Pandas.
- updated `setup.py`
- added Python 3.7
- updated docstring in `splitfuncs.py`

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.25.1...v0.25.2))
- updated `WorkingArea`
- catch generally `Exception` in `collect_result()` since the job
needs to be resubmitted regardless of the error type.
- cleaned code, updated test

Changes from the previous release: ([diff](https://github.com/alphatwirl/alphatwirl/compare/v0.25.0...v0.25.1))
- cleaned code, docstring, tests for `TaskPackageDropbox`