Minor improvement to fix minetest-mods#13

Picked up while testing  minetest-mods#34 and minetest-mods#30 that this needed to be adjusted from hitter name to hitter is player.

Hitter name was resolving to true even when mob was attacking...nil being counted as a value.

I should have picked this up before and not sure how I missed this.

3d_armor/init.lua

@@ -395,8 +395,8 @@ if armor.config.punch_damage == true then
 	minetest.register_on_punchplayer(function(player, hitter,
 			time_from_last_punch, tool_capabilities)
 		local name = player:get_player_name()
-		local name2 = hitter:get_player_name()
-		if name and name2 and minetest.is_protected(player:get_pos(), "") then
+		local hit_ip = hitter:is_player()
+		if name and hit_ip and minetest.is_protected(player:get_pos(), "") then
 			return
 		elseif name then
 			armor:punch(player, hitter, time_from_last_punch, tool_capabilities)