Reprexlite

- Added experimental IPython interactive editor which can be launched via command line with `reprex --ipython`. This modified IPython editor will run every cell automatically as a reprex.

- Added explicit setting of code evaluation namespace's `__name__` to `'__reprex__'`. Previously this was unset and would get inferred, and weird things like `'builtins'` would turn up. ([PR 44](https://github.com/jayqi/reprexlite/pull/44))

- Added support for parsing code copied from an interactive Python shell (REPL) with `>>>` prompts. ([29](https://github.com/jayqi/reprexlite/pull/29))
- Fixed issue where `tests` module was unintentionally included in distribution. ([30](https://github.com/jayqi/reprexlite/pull/30))
- Fixed missing requirement `importlib_metadata` for Python 3.6 and 3.7. ([31](https://github.com/jayqi/reprexlite/pull/31))

- Added missing LICENSE file.

- Added optional IPython extension that enables `%%reprex` cell magic. See [documentation](https://jayqi.github.io/reprexlite/stable/ipython-jupyter-magic/) for usage. ([#21](https://github.com/jayqi/reprexlite/pull/21))

- Documentation improvements. ([14](https://github.com/jayqi/reprexlite/pull/14), [#19](https://github.com/jayqi/reprexlite/pull/19))