issue #90 - Implementation of --execute on html format

[aless80]

Implementation of the --execute option, which executes code blocks. This s now implemented for the html, latex/pdflatex, ipynb formats and for doconce jupyterbook. The lib/doconce/html.py had code to render (unexecuted) code blocks. However, I hd to completely rework that part of code. I modularized much of the code so that latex.py and html.py can reuse it. I did not touch ipynb.py. I made sure that postfixes ['hid', '-h', '-e', '-t', 'out'] to code block environents work in both the latex and html formats. Same for code blocks using Sage (!bc pyscpro)

postfix	Effect on code block
hid	Hide the cell (but not in ipynb)
-e	Hide the cell (also in ipynb)
-t	Code as text
-h	Show/Hide button in html
out	Output cell

[lexnederbragt]

Thanks! Testing now. Was it a deliberate choice to have In [1]: in front of code blocks in html? I'd think this is not needed as it is a ipynb thing?

[aless80]

Yes, I had that idea and after that didn't give it much thought. I copied the html+css styling from a Jupyter Notebook. Other than that is the formatting of the input and output cells ok? Should I remove only that In [1] or do more modifications?

[lexnederbragt]

Please remove it, it should not be present in html. The rest looks OK.