use more precise timer for cooldown

game.lua

@@ -6,7 +6,6 @@ local Object = dofile(modpath .. DIR_DELIM .. "classic.lua")
 local snowgame = {}
 
 
-
 yl_snowball.GAME_TIMEOUT = 10 -- FIXME increase
 
 local active_games = {}

internal.lua

@@ -85,7 +85,7 @@ yl_snowball.on_use = function(itemstack, user, pointed_thing)
     local player = user
     local player_name = player:get_player_name()
 
-    local current_time = os.clock() --core.get_gametime() -- gametime seems to "lag"?
+    local current_time = core.get_us_time() --core.get_gametime() -- gametime seems to "lag"?
     if current_time - (player_last_throw_time[player_name] or 0) < yl_snowball.COOLDOWN then
         -- too soon, don't shot, don't take items
         return nil