Wow Mael, I was looking for something like this.
But to add the npc script, you would need to make a txt file and edit scripts_custom.conf
First, go to file location rAthena\npc\custom
Make a txt document and name it something like "AllInOneNPC.txt"
Copy and paste Mael's script into the txt, Save and close
Next we edit scripts_custom.conf
Go to rAthena\Npc <----- to find scripts_custom.conf
Edit and add something like
npc: npc/custom/AllInOneNPC.txt anywhere.
There are some scripts already in there, you can just delete the // to activate them.