Py-pip

- [feature] Use symlinks on Windows when symlinks are available

- [bugfix] Improved error reporting during venv metadata inspection.
- [bugfix] Fixed incompatibility with pypy as venv interpreter (372).
- [bugfix] Replaced implicit dependency on setuptools with an explicit dependency on packaging (339).
- [bugfix] Continue reinstalling packages after failure
- [bugfix] Hide cursor while pipx runs
- [feature] Add environment variable `USE_EMOJI` to allow enabling/disabling emojis (376)
- [refactor] Moved all commands to separate files within the commands module (255).
- [bugfix] Ignore system shared libraries when installing shared libraries pip, wheel, and setuptools. This also fixes
an incompatibility with Debian/Ubuntu's version of pip (386).

- [bugfix] On Windows, pipx now lists correct Windows apps (217)
- [bugfix] Fixed a `pipx install` bug causing incorrect python binary to be used when using the optional --python
argument in certain situations, such as running pipx from a Framework python on macOS and specifying a non-Framework
python.

- [bugfix] Fix recursive search of dependencies' apps so no apps are missed.
- `upgrade-all` now skips editable packages, because pip disallows upgrading editable packages.

- [bugfix] fix regression that caused installing with --editable flag to fail package name determination.

- Add Python 3.8 to PyPI classifier and travis test matrix
- [feature] auto-upgrade shared libraries, including pip, if older than one month. Hide all pip warnings that a new
version is available. (264)
- [bugfix] pass pip arguments to pip when determining package name (320)