Ragdoll plugin changes

[AlexandrKedrov]

• Fixed bug When player leave server after his death, his ragdoll is in not removed as it is done with player:set_ragdoll_state(RAGDOLL_NONE) called in PlayerSpawn hook. So it was moved into the create_ragdoll_entity function.
• Typo Decay is a bit ambiguous parameter name, so it was renamed into delay
• Feature Corpse removement delay was moved into config.yml
• To be negotiated Is it better to store delay parameter in the separated table that is passed to set_ragdoll_state as parameter or initialize it directly in this method Also, whether there are any others way to call PlayerDeathThink hook without calling player:is_ragdolled() method, that would allow to delete corpses before player respawned

PS sorry for the messy first pull request.

[Meow]

should have probably renamed into decay_time. I see a few other issues with the code but I'll need to be properly on my PC to really comment on them. I'll get back to you in a few.