Question regarding periodic_checkpoint_folder

Hi!
First of all, thanks again for the development of tpot!

When I create a `TPOTClassifier`, I specify folders both in `periodic_checkpoint_folder` and `memory` arguments.

I thought that by making these checkpoints, I would be able to resume the search in case my script was suddenly stopped, given that the information was saved both by the checkpoints and the memory cache. However, from what I can see in the documentation (and from my trials) this is not possible.

Can you confirm whether this is indeed not possible? If that's the case, I'd like to suggest that as a new feature!