Acacia bush: Create a unique form different to normal bush, with more
leaf nodes at top than at base.
Acacia tree: Maximum height increased by 1 node. 2 extra nodes of
height variation.
Jungle tree: Add an extra node of height variation. Y-slices moved
downwards to be more balanced between trunk and branches, makes
branches more common.
Pine tree: Increase maximum height by 1 node. Add an extra node of
height variation.
Update sapling 'on place' protection checks for acacia and pine trees.
Denser jungletree for darker rainforest:
Highest 'jungletree' nodes now prob 255.
Add a 5th lower branch layer.
Increase lower branch layer y-slice prob to 191.
Aspen:
Extend trunk upwards by 1 node to reduce leafdecay radius to 2.
Pine:
Make lower trunk 1 node longer so that lowest branches are more often
higher off the ground, also to make pines taller.
Appletree:
Make 2 opposite branches prob 255, the other 2 prob 127, to avoid
trees with 1 or 0 branches. Therefore also add random rotation.
