Make placed leaves always become player leaves

Any players which still have leaves in their inventory from before this update would have had those leaves rot if someone were to break any log withing 6 nodes of the leaves if they were placed. This commit adds an `after_place_node` callback which makes sure that any leaves placed by the player, become non-rotting player leaves.

mods/ITEMS/mcl_core/nodes_trees.lua

@@ -44,6 +44,14 @@ function mcl_core.update_leaves(pos, oldnode)
 	end
 end
 
+function mcl_core.make_player_leaves(pos)
+	local node = minetest.get_node(pos)
+		if minetest.get_item_group(node.name, "player_leaves") ~= 1 then
+			local playerleafname = node.name .. "_player"
+			minetest.set_node(pos, {name = playerleafname})
+	end
+end
+
 -- Register tree trunk (wood) and bark
 local function register_tree_trunk(subname, description_trunk, description_bark, longdesc, tile_inner, tile_bark, stripped_variant)
 	minetest.register_node("mcl_core:"..subname, {
@@ -207,10 +215,13 @@ local function register_leaves(subname, description, longdesc, tiles, color, par
 				minetest.swap_node(pos, new_node)
 			end
 		end
+	end,
+		after_place_node = function(pos)
+		mcl_core.make_player_leaves(pos) -- Leaves placed by the player should always be player leaves.
 	end,
 	}
 
-	minetest.register_node("mcl_core:player" .. subname, pl_def)
+	minetest.register_node("mcl_core:" .. subname .. "_player", pl_def)
 
 	local l_def = table.copy(pl_def)
 	l_def.groups.player_leaves = nil