Option to keep missing repositories in the list without prompting to remove them

I run SmartGit as a portable installation, shared between my desktop and my laptop. Most repositories are common to both machines, but each machine also has a few repositories that only exist locally on it (e.g. machine-specific scratch work or repos I haven't synced over yet).

Every time I launch SmartGit on one machine, it prompts me to remove the repositories that only live on the other machine. If I confirm, I lose them from the list on this machine and have to re-add them when I switch back. If I cancel, the prompt comes back on the next launch.

It would be very helpful to have a low-level property (e.g. `repositories.promptForMissing=false`) that keeps missing repositories in the list silently, grayed out as they already are, without showing the removal dialog on startup. The dialog could still be triggered on demand by clicking the missing repository, which is already the existing behavior.

This would make portable/multi-machine setups much smoother without changing any default behavior for regular users.