Make cells not dependent on predecessor

[benkeil]

Imagine you have 10 cells and you change the package imports.
Then I would like to rerun e.g. only the last cell and not evaluate everything before.

[jonatanklosko]

Since Livebook v0.8.0 we track dependencies between cells based on used variables, modules, imports, etc. The Setup cell is special though, to rerun that cell we always restart the runtime (because Mix.install can be called only once), so it's not that it just invalidates other cells, but it effectively resets all the evaluation state.

[josevalim]

You can also use branched sections if you want to run experiments isolated from others.