improve visualisation/formatting of latex in the notebook

[chrisjsewell]

This has previously been achieved (to some extent), as jupyter notebook extension, by jupyter_latex_envs. But, at present, it doesn't appear to have been updated for notebook 5.0 and was quite buggy when I tried it out (e.g. sometimes altering the text and pressing shift-Enter, the text reverted to back its initial value)

[chrisjsewell]

raised issue jfbercher/jupyter_latex_envs#25