renames take_damage() for organs to receive_damage()
renames Deconstruct() to deconstruct() for atmos objects
obj_integrity, max_integrity, integrity_failure vars moved to /obj level, obj_integrity = max_integrity on New()
Currently, to_chat is literally just a proc that does user << message.
But it'll let us do output modification in the future, especially for
something like Goon's HTML chat.
Big thanks to PJB for his to_chat script, see
https://github.com/d3athrow/vgstation13/pull/6625 for more details.
