Added mcl_luck API

Luck and Bad Luck effects use the mcl_luck API now
The API is unused for now

mods/ITEMS/mcl_potions/functions.lua

@@ -610,10 +610,13 @@ mcl_potions.register_effect({
 		return (not object:is_player())
 	end,
 	on_start = function(object, factor)
--- 		mcl_luck.add_luck_modifier(object, "mcl_potions:luck", factor)
+		mcl_luck.apply_luck_modifier(object:get_player_name(), "mcl_potions:luck", factor)
+	end,
+	on_load = function(object, factor)
+		mcl_luck.apply_luck_modifier(object:get_player_name(), "mcl_potions:luck", factor)
 	end,
 	on_end = function(object)
--- 		mcl_luck.remove_luck_modifier(object, "mcl_potions:luck")
+		mcl_luck.remove_luck_modifier(object:get_player_name(), "mcl_potions:luck")
 	end,
 	uses_factor = true,
 })
@@ -626,10 +629,13 @@ mcl_potions.register_effect({
 		return (not object:is_player())
 	end,
 	on_start = function(object, factor)
--- 		mcl_luck.add_luck_modifier(object, "mcl_potions:bad_luck", -factor)
+		mcl_luck.apply_luck_modifier(object:get_player_name(), "mcl_potions:bad_luck", -factor)
+	end,
+	on_load = function(object, factor)
+		mcl_luck.apply_luck_modifier(object:get_player_name(), "mcl_potions:bad_luck", -factor)
 	end,
 	on_end = function(object)
--- 		mcl_luck.remove_luck_modifier(object, "mcl_potions:bad_luck")
+		mcl_luck.remove_luck_modifier(object:get_player_name(), "mcl_potions:bad_luck")
 	end,
 	uses_factor = true,
 })

mods/PLAYER/mcl_luck/init.lua

@@ -0,0 +1,33 @@
+mcl_luck = {}
+
+-- table indexed by player name
+-- each entry for each player contains list of modifiers applied to the player
+-- modifiers are listed by their name (defined when applying them)
+-- all modifiers are dynamic (they are removed when the player leaves game and on server shutdown)
+local applied_luck = {}
+
+function mcl_luck.apply_luck_modifier(player_name, modifier_name, amount)
+	applied_luck[player_name][modifier_name] = amount
+end
+
+function mcl_luck.remove_luck_modifier(player_name, modifier_name)
+	applied_luck[player_name][modifier_name] = nil
+end
+
+function mcl_luck.get_luck(player_name)
+	local luck = 0
+	for _, amount in pairs(applied_luck[player_name]) do
+		luck = luck + amount
+	end
+	return luck
+end
+
+minetest.register_on_joinplayer(function(player)
+	local player_name = player:get_player_name()
+	applied_luck[player_name] = {}
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	local player_name = player:get_player_name()
+	applied_luck[player_name] = nil
+end)

mods/PLAYER/mcl_luck/mod.conf

@@ -0,0 +1,3 @@
+name = mcl_luck
+author = Herowl
+description = An API for handling luck, it can be polled by random events.