Be more specific about the tasks involved in developing a Jupyter interface

[mardukbp]

I believe that leveraging Xeus, a C++ implementation of the Jupyter kernel protocol, what Texmacs needs in order to become an alternative interface to the official web-based one is an implementation of the notebook, which involves writing Scheme, C++ , and a Texmacs stylesheet. Of course, one can use the IPython kernel to test the interface.

Some of the tasks involved are:

• Write an importer/exporter of notebook files.
• Refactor the syntax highlighting support in Texmacs. Adding lexers for new languages should not require recompiling the program.
• Implement modal cells: normal mode and insert mode like in vim.
• Mark multiple cells, cut and paste cells.
• Use the same keyboard shortcuts as the Jupyter notebook.