[Minor]Can't plant pumpkin on planter

[Battosay]

Title says it all.
Not that it would have any real use, but I just realized that while testing my prototype.

[FlowerChild]

Going to leave this one as is. I just took a look at the code, and I'd need to modify the pumpkin base-class for this to work, which would likely modify world-gen (since world gen for the pumpkins uses the same function I'd need to change).

It's because pumpkins need a solid block beneath them to be placed.

Anyways, going to leave this alone, as like you said, it doesn't have much use and would be opening a big can of worms to fix.