Fix attack messages from animals,blob,slimes on humans

* span classes instead of \red
* Attacks by simple animals, blob and slimes now gives a bold red message for the human target and red message for the other viewers.
* Replace "for(var/mob/O in viewers(src, null)) + show_message" stuff by visible_message() proc.
* blob attacks on humans now give a message to all viewers not just the target.