Add refund config option when you delete a plot

[WalrusSlayer]

PlotSquared Feature Suggestion: So people can still purchase plots elsewhere, allow them to get a refund when they delete it. Can be a simple config option to enable/disable it.

How should it be implemented? Simple config option true/false 'refund-plot-on-deletion'.

Additional context

Checklist:

• [x] I made sure there are no duplicates of my suggestion (Use search)
• [X] I made sure my suggestion does not exist yet (Check the wiki)
• [X] I made sure my suggestion is useful for the majority of PlotSquared users

[AeSix]

I think allowing the /option/ is a good idea, as owners can choose to not use it. Some possible issues may arise from this, such as trolls abusing it to constantly move around the map (potentially to harass someone who has moved their plot away from the troll)

On the same hand, it would allow people to move plots more easily, without staff intervention.

Therefore, I append this suggestion to have a cool-down period between refunds, owner defined from minutes to days.

[WalrusSlayer]

That's a great idea. An optional cooldown length would stop trolling.