Visible_message() now uses recursive_hear_check 

* 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. The mob is back in the paicard and should be able to hear sounds, visible_message, speech, audible_message. This should fix #5834 , #6045 , #5729 , #2947 , #5759 and #810 .
* Removing some no longer needed instances of occupant_message() in mecha code.
* Fixed some typos and span class here and there.