Even when just placing down a fence in an empty block space, it's placed as a multipart container. This should only happen when something already exists in the block space!

This is the same issue I had mentioned in #8 and if fixed would make #11 also unnecessary as regularly placed fences (ie. not multiblock) supporting leads would be expected behavior.

Yeah, the fence placement code needs some cleanup. #11 is still something I'd like to add at some point, though.