Bonemealing mechanics bugfix.

When applying bonemeal to eg. farm crops, these have a chance to grow in
response to the application of bone meal. When a node can be bonemealed, the
applied bone meal item should always be spent after using it, regardless of
the results.  Currently this does not work correctly, if the result of
bonemealing has no effect on the node, the used bone meal item is not spent.

This commit fixes the behavior of the bone meal item to always be taken when
used on a node that defines a `_mcl_on_bonemealing()` callback.

The nodes that implement the callback imay use the handler's return value
only to signal if the bonemealing was succesful, not to signal if it was at
all possible.  For this reason, some nodes need to be made more strictly
conforming to the API.

* Always take the used bone meal item (if user is not in creative mode),
  regardless of whether the bonemealed node's handler returned `true`.
* Make dispensers spawn particles after succesful bonemealing.
* Trivial comment fix.
* Ripe cocoa pod cannot be bonemealed.
* Update API.md to describe the stricter API semantics.

mods/ITEMS/mcl_bone_meal/API.md

@@ -8,7 +8,17 @@ The bone meal API provides a callback definition that nodes can use to
 register a handler that is executed when a bone meal item is used on it.
 
 Nodes that wish to use the bone meal API should in their node registration
-define a callback handler named `_mcl_on_bonemealing`.  This handler is a
+define a callback handler named `_mcl_on_bonemealing`.
+
+Note that by registering the callback handler, the node declares that bone
+meal can be used on it and as a result, when the user is not in creative
+mode, the used bone meal is spent and taken from the itemstack passed to
+the `on_place()` handler of the bone meal item used.
+
+It is for all intents and purposes up to the callback defined in the node to
+decide how to handle the specific effect that bone meal has on that node.
+
+The `_mcl_on_bonemealing` callback handler is a
 
   `function(pointed_thing, placer)`
 
@@ -17,10 +27,9 @@ Its arguments are:
 	bone meal is applied
 * `placer`: ObjectRef of the player who aplied the bone meal, can be nil!
 
-The function should return `true` if the bonemealing was succesful.
-
-It is for all intents and purposes up to the callback defined in the node to
-decide how to handle the effect that bone meal has on that particular node.
+The return value of the handler function indicates if the bonemealing had
+its intended effect.  If `true`, 'bone meal particles' are spawned at the
+position of the bonemealed node.
 
 The `on_place` code in the bone meal item will spawn bone meal particles and
 decrease the bone meal itemstack if the handler returned `true` and the

mods/ITEMS/mcl_bone_meal/init.lua

@@ -49,7 +49,7 @@ end
 --
 mcl_bone_meal.bone_meal_callbacks = {}
 
--- Shims for the old API are still available in mcl_dye and refer to
+-- Shims for the old API are still available in mcl_dye and defer to
 -- the real functions in mcl_bone_meal.
 --
 function mcl_bone_meal.register_on_bone_meal_apply(func)
@@ -91,9 +91,9 @@ minetest.register_craftitem("mcl_bone_meal:bone_meal", {
 		if ndef and ndef._mcl_on_bonemealing then
 			if ndef._mcl_on_bonemealing(pointed_thing, placer) then
 				mcl_bone_meal.add_bone_meal_particle(pos)
-				if not minetest.is_creative_enabled(placer:get_player_name()) then
-					itemstack:take_item()
-				end
+			end
+			if not minetest.is_creative_enabled(placer:get_player_name()) then
+				itemstack:take_item()
 			end
 		-- Otherwise try the legacy API.
 		elseif apply_bone_meal(pointed_thing, placer) and
@@ -114,8 +114,9 @@ minetest.register_craftitem("mcl_bone_meal:bone_meal", {
 		-- If the pointed node can be bonemealed, let it handle the processing.
 		if ndef and ndef._mcl_on_bonemealing then
 			if ndef._mcl_on_bonemealing(pointed_thing, nil) then
-				itemstack:take_item()
+				mcl_bone_meal.add_bone_meal_particle(pos)
 			end
+			itemstack:take_item()
 		else
 			-- Otherwise try the legacy API.
 			if apply_bone_meal(pointed_thing, nil) then

mods/ITEMS/mcl_cocoas/init.lua

@@ -167,6 +167,7 @@ for i = 1, 3 do
 	end
 	if i == 3 then
 		def.drop = "mcl_cocoas:cocoa_beans 3"
+		def._mcl_on_bonemealing = nil
 	end
 
 	minetest.register_node("mcl_cocoas:cocoa_" .. i, table.copy(def))