Remove saplings and every TreeType when they grow from placed blocks

[ErikSzabo]

Fixes #243

This will remove the placed sapling/mushroom and everything from the TreeType enum from the placed blocks when they grow naturally or via bonemeal, so placed blocks that are converted into natural blocks can give skill XP.

[ErikSzabo]

@Archy-X here is the revised version of #244. I think this is a far better and more complete solution than the previous one.