Add the /regen, /undo, and /redo commands

Sometimes, after using the /fill or /setblock commands, you might need to remove that action. It would be nice to have an /undo command to fix this. If a player accidentally undoes something they didn't mean to mark, the /redo command would be necessary.

 

Even so, these two commands alone aren't enough, as sometimes a player can make a mistake and flood the entire forest with lava. It would also be nice to have a /regen command to restore the entire selected area to its original state. Alternatively, instead of this command, we could add a command to roll back the selected part of the world for a certain period of time. This would be especially helpful if someone was griefed on local servers, without plugins or mods.