Schematics: Various improvements

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.

mods/default/nodes.lua

@@ -882,7 +882,7 @@ minetest.register_node("default:pine_sapling", {
 			-- minp, maxp to be checked, relative to sapling pos
 			-- minp_relative.y = 1 because sapling pos has been checked
 			{x = -2, y = 1, z = -2},
-			{x = 2, y = 12, z = 2},
+			{x = 2, y = 14, z = 2},
 			-- maximum interval of interior volume check
 			4)
 
@@ -962,7 +962,7 @@ minetest.register_node("default:acacia_sapling", {
 			-- minp, maxp to be checked, relative to sapling pos
 			-- minp_relative.y = 1 because sapling pos has been checked
 			{x = -4, y = 1, z = -4},
-			{x = 4, y = 6, z = 4},
+			{x = 4, y = 7, z = 4},
 			-- maximum interval of interior volume check
 			4)