handrails (#3002)

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## About The Pull Request
This adds handrails, from Baystation - original PR that added them is
[here](Baystation12/Baystation12#18474). This
doesn't actually add anything to any maps, but adds it as a structure
for mappers to use. I did a little bit of work by adding a crafting
recipe, and simplifying things by making it a chair subtype.
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## Why It's Good For The Game
It's like. You can grab onto them. Makes Zero-G ships better, helps with
transits so people don't go awkwardly rushing to chairs or just flop to
the floor.
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## Changelog

:cl: fighterslam, comma
add: Handrails, rails on the wall that you can grab/buckle yourself to.
(*Not included in any maps with this PR, but craftable with 4 iron
rods.)
:cl:

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code/game/objects/items/stacks/rods.dm

@@ -9,6 +9,7 @@ GLOBAL_LIST_INIT(rod_recipes, list ( \
 	new/datum/stack_recipe("modern railing corner", /obj/structure/railing/modern/corner, 1, time = 10, window_checks = TRUE), \
 	new/datum/stack_recipe("modern railing end", /obj/structure/railing/modern/end, 3, time = 18, window_checks = TRUE), \
 	new/datum/stack_recipe("ladder", /obj/structure/ladder/crafted, 15, time = 150, one_per_turf = TRUE, on_floor = FALSE), \
+	new/datum/stack_recipe("handrail", /obj/structure/chair/handrail, 4, time = 15, one_per_turf = TRUE), \
 	))
 
 /obj/item/stack/rods

code/game/objects/structures/beds_chairs/chair.dm

@@ -355,3 +355,12 @@
 	custom_materials = list(/datum/material/plastic = 2000)
 	break_chance = 25
 	origin_type = /obj/structure/chair/plastic
+
+/obj/structure/chair/handrail
+	name = "handrail"
+	icon = 'icons/obj/structures/handrail.dmi'
+	icon_state = "handrail"
+	desc = "A safety railing with buckles to secure yourself to when floor isn't stable enough."
+	item_chair = null
+	buildstackamount = 4
+	buildstacktype = /obj/item/stack/rods