Add player inventory callbacks

doc/lua_api.txt

@@ -2880,6 +2880,22 @@ Call these functions only at load time!
 * `minetest.register_craft_predict(func(itemstack, player, old_craft_grid, craft_inv))`
     * The same as before, except that it is called before the player crafts, to
       make craft prediction, and it should not change anything.
+* `minetest.register_allow_player_inventory_action(func(player, inventory, action, inventory_info))`
+    * Determinates how much of a stack may be taken, put or moved to a
+      player inventory.
+    * `player` (type `ObjectRef`) is the player who modified the inventory
+      `inventory` (type `InvRef`).
+    * List of possible `action` (string) values and their
+      `inventory_info` (table) contents:
+        * `move`: `{from_list=string, to_list=string, from_index=number, to_index=number, count=number}`
+        * `put`:  `{listname=string, index=number, stack=ItemStack}`
+        * `take`: Same as `put`
+    * Return a numeric value to limit the amount of items to be taken, put or
+      moved. A value of `-1` for `take` will make the source stack infinite.
+* `minetest.register_on_player_inventory_action(func(player, inventory, action, inventory_info))`
+    * Called after a take, put or move event from/to/in a player inventory
+    * Function arguments: see `minetest.register_allow_player_inventory_action`
+    * Does not accept or handle any return value.
 * `minetest.register_on_protection_violation(func(pos, name))`
     * Called by `builtin` and mods when a player violates protection at a
       position (eg, digs a node or punches a protected entity).