fonsp
Allow changes while waiting for binder backend
We currently disable editing while waiting for the binder backend to connect, which is annoying. Instead, we should save up the patches until we connect, and send all patches in one go afterwards.
This would allow me to export an empty notebook to HTML, host that online, and we have online Pluto with instant editing.
For this one, it would be nice to first remove the responses[:run_multiple_cells] action, and make that part of effects_of_changed_state. E.g. each cell could have fields run_requested_at, run_performed_at. When you press Shift+Enter, run_requested_at is increased, and when the backend starts that run, it sets cell.run_performed_at = cell.run_requested_at. This is also related to #220