Improve NPC pseudo-respawning

In initial testing, longer periods were better. However, that was before
a lot of recoding... shorter periods are now superior and keeping
significantly more NPCs visible (When dealing with batches so large that
the system fails to load them all)

src/main/java/net/citizensnpcs/npc/entity/HumanController.java

@@ -93,7 +93,7 @@ public class HumanController extends AbstractEntityController {
                     NMS.sendPlayerlistPacket(false, null, npc);
                 }
             }
-        }, 60);
+        }, 2);
         return handle.getBukkitEntity();
     }
 

src/main/java/net/citizensnpcs/util/NMS.java

@@ -512,7 +512,7 @@ public class NMS {
                     sendPlayerlistPacket(false, player, npc);
                 }
             }
-        }, 61);
+        }, 2);
     }
 
     public static org.bukkit.entity.Entity spawnCustomEntity(org.bukkit.World world, Location at,