Allow keeping the previous container indefinitely

[Philipp Daun]

Describe the problem

• Currently, the plugin discards the previous content after the animation
• Some layouts require keeping a copy of the previous content indefinitely
• Stacked layouts, multi-column slideshows, etc.

Describe the proposed solution

• Add an option to keep X previous content containers around
• Think about browser history visits

Alternatives considered

• Create a project-specific plugin or use hooks with custom logic

How important is this feature to you?

• Nice to have
• Would make my life a lot easier
• I cannot use swup without it