Add afterbuckle proc to beds, refactor comfychairs

This commit ports Baystation12/Baystation12#8527, as well as their
afterbuckle system. After a mob is buckled/unbuckled, afterbuckle will be
called on the object, which does nothing by default.

Comfy Chairs have been refactored to use a grayscale sprite, and also to
use overlays for the arms. This means that new colors are just a RGB
definition.

code/game/objects/structures/stool_bed_chair_nest/bed.dm

@@ -54,13 +54,20 @@
 	buckle_mob(M, user)
 	return
 
+/obj/structure/stool/bed/proc/afterbuckle(mob/M as mob) //Called after somebody buckled / unbuckled
+	return
+
 /obj/structure/stool/bed/proc/unbuckle()
 	if(buckled_mob)
 		if(buckled_mob.buckled == src)	//this is probably unneccesary, but it doesn't hurt
 			buckled_mob.buckled = null
 			buckled_mob.anchored = initial(buckled_mob.anchored)
 			buckled_mob.update_canmove()
+
+			var/M = buckled_mob
 			buckled_mob = null
+
+			afterbuckle(M)
 	return
 
 /obj/structure/stool/bed/proc/manual_unbuckle(mob/user as mob)
@@ -110,6 +117,7 @@
 	M.update_canmove()
 	src.buckled_mob = M
 	src.add_fingerprint(user)
+	afterbuckle(M)
 	return
 
 /*

code/game/objects/structures/stool_bed_chair_nest/chairs.dm

@@ -97,26 +97,53 @@
 /obj/structure/stool/bed/chair/comfy
 	name = "comfy chair"
 	desc = "It looks comfy."
+	icon_state = "comfychair"
+	color = rgb(255,255,255)
+	var/image/armrest = null
+
+/obj/structure/stool/bed/chair/comfy/New()
+	armrest = image("icons/obj/objects.dmi", "comfychair_armrest")
+	armrest.layer = MOB_LAYER + 0.1
+
+	return ..()
+
+/obj/structure/stool/bed/chair/comfy/afterbuckle()
+	if(buckled_mob)
+		overlays += armrest
+	else
+		overlays -= armrest
 
 /obj/structure/stool/bed/chair/comfy/brown
-	icon_state = "comfychair_brown"
+	color = rgb(141,70,0)
 
-/obj/structure/stool/bed/chair/comfy/beige
-	icon_state = "comfychair_beige"
+/obj/structure/stool/bed/chair/comfy/red
+	color = rgb(218,2,10)
 
 /obj/structure/stool/bed/chair/comfy/teal
-	icon_state = "comfychair_teal"
+	color = rgb(0,234,250)
+
+/obj/structure/stool/bed/chair/comfy/black
+	color = rgb(60,60,60)
+
+/obj/structure/stool/bed/chair/comfy/green
+	color = rgb(1,196,8)
+
+/obj/structure/stool/bed/chair/comfy/purp
+	color = rgb(112,2,176)
+
+/obj/structure/stool/bed/chair/comfy/blue
+	color = rgb(2,9,210)
+
+/obj/structure/stool/bed/chair/comfy/beige
+	color = rgb(255,253,195)
+
+/obj/structure/stool/bed/chair/comfy/lime
+	color = rgb(255,251,0)
 
 /obj/structure/stool/bed/chair/office
 	anchored = 0
 	movable = 1
 
-/obj/structure/stool/bed/chair/comfy/black
-	icon_state = "comfychair_black"
-
-/obj/structure/stool/bed/chair/comfy/lime
-	icon_state = "comfychair_lime"
-
 /obj/structure/stool/bed/chair/office/Move()
 	..()
 	if(buckled_mob)