Minimal extend branch and collapse functions

[phraenquex]

This might be a become a big ticket, or seed many tickets - endpoint not yet defined, it's a placeholder to be fleshed out in the first discussion after the current milestone is almost done (#432).

When clicking on the end of a branch, stay on the branch. When clicking upstream (in the past) create a new branch.

Allow selecting and collapse of a branch

[reskyner]

https://app.conceptboard.com/board/5fxc-5xcz-7hds-zgkc-kn9a

[boriskovar-m2ms]

Could you please clarify the last part? The 'Allow selecting and collapse of a branch'? Because first part of the ticket is actually already implemented.

[phraenquex]

I'd need to show this interactively, but the use case is: if I've done a lot of action on a branch, there will (might) be many nodes, which I won't (generaly) want to see - so

• allow me to select them all (drag) and collapse them into a single icon, e.g. a ➕;
• allow me to open them all up by some click (double-click?) on that ➕

(Later, node pruning probably will also become relevant, but let's stick to this for now.)