Natura trees don't generate correctly on different ground types.

[temp1011]

Minecraft: 1.12 Forge: 14.23.2.2624 Mantle: 1.3.1.21 Natura: 1.12.2-4.3.2.42 Natura trees will grow underneath different blocks to dirt and grass if planted on a different soil. For example, using forestry humus:

Looks like some kind of Material.GROUND check is needed when generating eg- https://github.com/progwml6/Natura/blob/2f9ab9a7ecbdaf41b7b44a9da9ed134b8090fb3f/src/main/java/com/progwml6/natura/world/worldgen/trees/overworld/EucalyptusTreeGenerator.java#L135 has problems but https://github.com/progwml6/Natura/blob/2f9ab9a7ecbdaf41b7b44a9da9ed134b8090fb3f/src/main/java/com/progwml6/natura/world/worldgen/trees/overworld/OverworldTreeGenerator.java#L73 is fine I think.