Back up and reload ipynb files onto the device

[goatchurchprime]

If this becomes a primary interface, then it can be backed up and reloaded into and out of the device itself

It may be possible to fetch the ipynb file that we are operating on, but how to bring it back and reload it?

Maybe two way file saving and loading will get there

[goatchurchprime]

Probably more as a cell_by_cell thing into different files, where each cell does a
from cell9 import * on the previous cell so that it can (almost) work

Either that or separate the cells with a structured comment. Probably this is better.

Maybe block each block into an if-statement to make the cells choosable.