Jupytext

- Python file format updated to 1.1: default end of cell for python scripts is
one blank space. Two blank spaces are allowed as well. Now you can reformat
code in Python IDE without breaking notebook cells (38).
- Added support for plain markdown files (40, 44).
- Demonstration notebooks more user friendly (45).
- Command line tool simpler to use (46).
- Start code patterns present in Jupyter cells are escaped.
- Default `nbrmd_format` is empty (mwouts/nbsrc/5): no Jupyter notebook
is created on disk when the user opens a Python or R file and saves it from
Jupyter, unless the users asks for it by setting `nbrmd_format`.

**BugFixes**

- Fixed message in the `nbsrc` script (43)
- Technical metadata don't appear any more in scripts unless required (42)
- Code cells that are fully commented remain code cells after round trip (41)

**Changed**
- The CI has been updated. Thanks to [Christian Le](https://github.com/LecrisUT) for taking care of this! ([#1190](https://github.com/mwouts/jupytext/issues/1190), [#1204](https://github.com/mwouts/jupytext/issues/1204))

**Fixed**
- Fixed an issue about unpairing notebooks from the Jupytext Menu ([1197](https://github.com/mwouts/jupytext/issues/1197))
- JupyterLab's dependency `follow-redirects` was updated from 1.15.3 to 1.15.4 ([1203](https://github.com/mwouts/jupytext/issues/1203))

**Added**
- The Jupytext Menu is back! And text notebooks can be created directly from the launcher. This is an outstanding contribution by [Mahendra Paipuri](https://github.com/mahendrapaipuri) ([#1154](https://github.com/mwouts/jupytext/issues/1154), [#1163](https://github.com/mwouts/jupytext/issues/1163)). This requires JupyterLab 4.x or Jupyter Notebook 7.x.

**Changed**
- Jupytext is now configured with `pyproject.toml` and built with `hatch`. The layout has been reorganised to follow `src-layout` ([1140](https://github.com/mwouts/jupytext/issues/1140)). This is another outstanding contribution by [Mahendra Paipuri](https://github.com/mahendrapaipuri).
- The tests are now part of the `sdist`. They have been reorganized into unit/functional/integration/external ([1167](https://github.com/mwouts/jupytext/issues/1167), [#1173](https://github.com/mwouts/jupytext/issues/1173)).
- The legacy extension for Jupyter Notebook <=6 (the Jupytext Menu) has been removed.

**Fixed**
- The bibliography section in Rmd files does not become a code cell anymore ([1161](https://github.com/mwouts/jupytext/issues/1161))
- Commented code in `active-py` cells is not uncommented anymore ([1131](https://github.com/mwouts/jupytext/issues/1131))
- The test coverage has been restored ([1167](https://github.com/mwouts/jupytext/issues/1167), [#1173](https://github.com/mwouts/jupytext/issues/1173))
- We test Jupytext against the pre-release version of JupyterLab, and other dependencies ([1168](https://github.com/mwouts/jupytext/issues/1168))

**Added**
- The Jupytext Menu is back! And text notebooks can be created directly from the launcher. This is an outstanding contribution by [Mahendra Paipuri](https://github.com/mahendrapaipuri) ([#1154](https://github.com/mwouts/jupytext/issues/1154), [#1163](https://github.com/mwouts/jupytext/issues/1163)). This requires JupyterLab 4.x or Jupyter Notebook 7.x.

**Changed**
- Jupytext is now configured with `pyproject.toml` and built with `hatch`. The layout has been reorganised to follow `src-layout` ([1140](https://github.com/mwouts/jupytext/issues/1140)). This is another outstanding contribution by [Mahendra Paipuri](https://github.com/mahendrapaipuri).
- The tests are now part of the `sdist`. They have been reorganized into unit/functional/integration/external ([1167](https://github.com/mwouts/jupytext/issues/1167), [#1173](https://github.com/mwouts/jupytext/issues/1173)).
- The legacy extension for Jupyter Notebook <=6 (the Jupytext Menu) has been removed.

**Fixed**
- The bibliography section in Rmd files does not become a code cell anymore ([1161](https://github.com/mwouts/jupytext/issues/1161))
- Commented code in `active-py` cells is not uncommented anymore ([1131](https://github.com/mwouts/jupytext/issues/1131))
- The test coverage has been restored ([1167](https://github.com/mwouts/jupytext/issues/1167), [#1173](https://github.com/mwouts/jupytext/issues/1173))
- We test Jupytext against the pre-release version of JupyterLab, and other dependencies ([1168](https://github.com/mwouts/jupytext/issues/1168))

**Added**
- The Jupyter Lab extension is now compatible with the [JupyterLab RISE](https://github.com/jupyterlab-contrib/rise) extension. Many thanks to [Frédéric Collonval](https://github.com/fcollonval) for his PR ([#1126](https://github.com/mwouts/jupytext/pull/1126))!

**Added**
- We have added a new command line interface `jupytext-config` that you can use to set Jupytext as the default viewer for text notebooks in Jupyter Lab and Jupyter Notebook 7. Thanks to [Thierry Parmentelat](https://github.com/parmentelat) for this contribution! ([#1094](https://github.com/mwouts/jupytext/pull/1094))