The necessary regex in `src/codemirror-finesse3-types.ts` is
generated manually by `generateregex.py`, as `finesse` isn't on PyPI at
the moment and so can't be used as a build requirement. In the future,
this could be done as part of the build, so the pre-made typescript file
can be removed.

Now some finesse syntax for codemirror just needs to be written.

Still neads an initial change to any part of the notebook to activate.