-tg- OOP Hud Refactor

- Added 4 new HUD styles
 - Humans recreate their hud if they change their UI pref mid-game
 - Refactored how objects are added to the client screen
 - HUD's are now handled by subtype and mob/proc/create_mob_hud()
 - HUD visibility is no longer chained directly to the F12 button, it's a proc on HUD datums now
 - Mobs only create/destroy their HUD when necessary, not every Login()
 - Destroyed aim-mode, it didn't work and I couldn't make it work.
 - Renamed all of the screen1_x.dmi files to screen_x.dmi
 - Removed screen1.dmi, screen_gen.dmi now handles generic icons.

code/modules/mining/machine_input_output_plates.dm

@@ -1,7 +1,7 @@
 /**********************Input and output plates**************************/
 
 /obj/machinery/mineral/input
-	icon = 'icons/mob/screen1.dmi'
+	icon = 'icons/mob/screen_gen.dmi'
 	icon_state = "x2"
 	name = "Input area"
 	density = 0
@@ -10,7 +10,7 @@
 		icon_state = "blank"
 
 /obj/machinery/mineral/output
-	icon = 'icons/mob/screen1.dmi'
+	icon = 'icons/mob/screen_gen.dmi'
 	icon_state = "x"
 	name = "Output area"
 	density = 0