re-added yl_speak_up.on_spawn to mobs.lua for now

mobs.lua

@@ -1,3 +1,23 @@
+-- assing ID at spawning (not at first talk) and log it
+function yl_speak_up.on_spawn(self)
+    --Let's protect it
+    self.protected = true
+    self.tamed = true
+    self.object:set_armor_groups({immortal = 100})
+
+    --Let's assign an ID (usually this happens at first talk)
+    self = yl_speak_up.initialize_npc(self)
+
+    if(not(self) or not(self.yl_speak_up) or not(self.yl_speak_up.id)) then
+        -- something went very wrong
+        return false
+    end
+    yl_speak_up.log_change("-", "n_"..self.yl_speak_up.id,
+            "spawned at "..minetest.pos_to_string(self.object:get_pos()), "action")
+    --Let's do it only once
+    return true
+end
+
 mobs:register_mob("yl_speak_up:human", {
   type = "npc",
   passive = true,