use .qmd as as full replacement of .ipynb

[tatakof]

hello!

wanted to know if it's possible to use only .qmd files for a full nbdev project (no .ipynb, all the code on .qmd) using nbdev's directives like so:

```{python}
#| default_exp core

\```

<some markdown>

```{python}
#| hide
from nbdev.showdoc import *

\```

<some markdown>

```{python}
#| export
def foo(): pass

\```

```{python}
#| hide
import nbdev; nbdev.nbdev_export()

\```
        

and get a result package with a core.py containing foo()

cheers,
Francis

[bhoov]

I've taken a stab at this issue in #1521. Feel free to try it out leave some comments in the PR if you have any issues:

pip install -U "git+https://github.com/bhoov/nbdev.git@qmd_support"

Then create a new .qmd file in your existing project with exports, docs, and tests. Alternatively, you can convert your entire .ipynb codebase to .qmd files following the tutorial section "Convert existing .ipynb codebase to .qmd":

1. Run nbdev_ipynb_to_qmd nbs nbs_qmd && mv nbs nbs_ipynb && mv nbs_qmd nbs to convert your .ipynb files to .qmd files (feel free to rm -r nbs_ipynb)
2. Update the readme_nb in settings.ini to be the new .qmd file
3. Run nbdev_prepare