Fixes more span classes. Replaces some "for() show_message()" with "visible_message()". Adding a suicide message for slimes. Fixes simple_animal/corgi having two attackby procs.
Merge branch 'master' of https://github.com/tgstation/-tg-station into SpanFix1

Conflicts:
	code/modules/mob/living/simple_animal/friendly/corgi.dm
Merge pull request #6127 from phil235/SpanFix1

Fixes span classes and show_message()'s