Powerline-shell

* Patch environment for VCS subprocesses rather than generating a new one
* Fix `cwd` segment so it respects `max_depth` configuration
* Fix Ruby segment for Python 3 compatibility
([Blue-Dog-Archolite](https://github.com/b-ryan/powerline-shell/pull/366))
* Configuration is now expected to be at
`~/.config/powerline-shell/config.json` ([emansije and
kc9jud](https://github.com/b-ryan/powerline-shell/pull/334))
* New `git_stash` segment
([apinkney97](https://github.com/b-ryan/powerline-shell/pull/379))

* Fix root user segment
([TiGR](https://github.com/b-ryan/powerline-shell/pull/362))
* Fixes and enhancements for SVN segment
([emansije](https://github.com/b-ryan/powerline-shell/pull/349))

* Bring back the ability to create custom themes
([b-ryan](https://github.com/b-ryan/powerline-shell/pull/352))
* Add the ability to customize the `time` segment in themes
([gaurav-nelson](https://github.com/b-ryan/powerline-shell/pull/338))

* VCS segments (git, hg, etc.) can now show a symbol identifying what VPS the
current directory uses
([emansije](https://github.com/b-ryan/powerline-shell/pull/298))

* Fix bug in SVN segment
([kc9jud](https://github.com/b-ryan/powerline-shell/pull/347))

* Fix `cwd` segment in Bash for Windows
([b-ryan](https://github.com/b-ryan/powerline-shell/pull/340))