Changes from the previous release: ([diff](https://github.com/alphatwirl/atpbar/compare/v0.9.6...v0.9.7))
- fixed the problem of progress bars stopping in multiprocessing.
- `atpbar` in sub-processes will not send the end order to the pickup.
- fixed the problem of duplicate progress bar for complete tasks.
- The last report will be sent only once for each task regardless of whether the loop completes all iterations.
- updated .travis.yml, using 3.7-dev for python 3.7
- updated tests
- cleaned code