Visible_message() now uses recursive_hear_check so mob inside something can see those messages. Fixes being able to see visible_message w/o seeing the src of it (happened when the src could see us but not the other way around), you no longer see visible_message from mobs inside closets for example.
Fixes pAI being deaf.
Removing some no longer needed occupant_message() in mecha code.
Fixed some typos and span class here and there.
Fixes visible_message's blind_message only being heard by actual blind mobs and not by other mobs who just cannot see the src in the dark. Now all non-deaf people in hearing range who did not get the "visible" message will instead get the "audible" blind_message.
Merge branch 'master' of https://github.com/tgstation/-tg-station into RecursiveHearVisibleMessage

Conflicts:
	code/game/machinery/doors/windowdoor.dm
	code/game/mecha/mecha.dm
	code/game/objects/structures.dm
	code/game/turfs/simulated/walls.dm
	code/modules/mob/living/carbon/human/human_defense.dm
	code/modules/mob/living/living_defense.dm
Merge branch 'master' of https://github.com/tgstation/-tg-station into RecursiveHearVisibleMessage

Conflicts:
	code/modules/reagents/Chemistry-Holder.dm
Changed the visible_message procs and audible_message procs, they now use the new get_player_mob_hearers_in_view() proc instead of a recursive proc.

I removed some duplicated code from tools/tools.dm

Fixed two typos with span class.
Reverting back to using the recursive get_hearers_in_view proc.
Merge pull request #6207 from phil235/RecursiveHearVisibleMessage

Mob inside something can now see visible_message()'s