Tree schematics: Alter jungletree, aspen, pine, appletree

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.

mods/default/mapgen.lua

@@ -1296,6 +1296,7 @@ function default.register_decorations()
 		y_max = 31000,
 		schematic = minetest.get_modpath("default") .. "/schematics/apple_tree.mts",
 		flags = "place_center_x, place_center_z",
+		rotation = "random",
 	})
 
 	minetest.register_decoration({