Prop gun effect (#4450)

# About the pull request

Adds an effect for a prop gun, where you enter the type path as its
variable and it automatically makes it look like the gun but unusable

(Codersprites should only be visible in mapping)
# Explain why it's good for the game

Makes it easier to map in destroyed or non-functional guns
# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog
:cl:
add: Added a mapping effect for prop guns
/:cl:

code/game/objects/effects/spawners/prop_gun_spawner.dm

@@ -0,0 +1,91 @@
+/obj/effect/spawner/prop_gun //Makes a prop that looks similar to the original gun, for use such as broken guns
+	name = "prop gun spawner"
+	icon = 'icons/landmarks.dmi'
+	icon_state = "prop_gun"
+	///The typepath of the gun the prop will copy
+	var/obj/item/weapon/gun/prop_gun_type = /obj/item/weapon/gun
+	///if the prop will have a custom name
+	var/custom_gun_name
+	///if the prob will have a custom desc
+	var/custom_gun_desc
+	///The probability of the prop gun spawning
+	var/spawn_prob = 100
+
+/obj/effect/spawner/prop_gun/Initialize(mapload, ...)
+	. = ..()
+	if(!ispath(prop_gun_type, /obj/item/weapon/gun))
+		stack_trace("[src] using incorrect typepath, \"[prop_gun_type]\".") //Can't make a prop gun of something not a gun
+		qdel(src)
+		return
+	if(!spawn_prob)
+		qdel(src)
+		return
+	if(!mapload)
+		prepare_gun_skin()
+		return
+	return INITIALIZE_HINT_ROUNDSTART
+
+/obj/effect/spawner/prop_gun/LateInitialize()
+	prepare_gun_skin()
+
+///Spawns the items and modifies source to set skin on prop
+/obj/effect/spawner/prop_gun/proc/prepare_gun_skin()
+	///The source, which the skin will be copied from
+	var/obj/item/weapon/gun/source_gun = new prop_gun_type(src)
+	if(custom_gun_name)
+		source_gun.name = custom_gun_name
+	if(custom_gun_desc)
+		source_gun.desc = custom_gun_desc
+	source_gun.pixel_x = pixel_x
+	source_gun.pixel_y = pixel_y
+	source_gun.layer = layer
+
+	///The prop itself, which the skin will be copied to
+	var/obj/item/prop/prop_gun/prop_gun = new /obj/item/prop/prop_gun(loc)
+	prop_gun.set_gun_skin(source_gun)
+	qdel(src)
+
+/obj/item/prop/prop_gun
+	name = "prop gun"
+	desc = "A non-functional gun prop. You should not be able to see this."
+	icon = 'icons/landmarks.dmi'
+	icon_state = "prop_gun"
+	flags_item = TWOHANDED
+	pickup_sound = "gunequip"
+	drop_sound = "gunrustle"
+	pickupvol = 7
+	dropvol = 15
+
+///Makes the gun look similar to the source, using the source as an atom reference
+/obj/item/prop/prop_gun/proc/set_gun_skin(obj/item/weapon/gun/source_gun)
+	if(!source_gun)
+		return
+	name = source_gun.name
+	desc = source_gun.desc
+	icon = source_gun.icon
+	item_icons = source_gun.item_icons
+	icon_state = source_gun.icon_state
+	item_state = source_gun.item_state
+	w_class = source_gun.w_class
+	flags_equip_slot = source_gun.flags_equip_slot
+	pixel_x = source_gun.pixel_x
+	pixel_y = source_gun.pixel_y
+	layer = source_gun.layer
+
+/obj/item/prop/prop_gun/attack_self(mob/user) //Mimic wielding of real guns
+	. = ..()
+	if(!(flags_item & TWOHANDED))
+		return
+	if(flags_item & WIELDED)
+		unwield(user)
+	else
+		wield(user)
+
+/obj/item/prop/prop_gun/dropped(mob/user)
+	..()
+	unwield(user)
+
+/obj/effect/spawner/prop_gun/m41aMK1
+	prop_gun_type = /obj/item/weapon/gun/rifle/m41aMK1
+	custom_gun_name = "\improper Broken M41A pulse rifle"
+	custom_gun_desc = "An older design of the Pulse Rifle commonly used by Colonial Marines. This one has seen better days. The trigger is missing, the barrel is bent, and it no longer appropriately feeds magazines."

code/modules/clothing/suits/marine_armor.dm

@@ -60,7 +60,8 @@
 	siemens_coefficient = 0.7
 	slowdown = SLOWDOWN_ARMOR_MEDIUM
 	allowed = list(
-		/obj/item/weapon/gun/,
+		/obj/item/weapon/gun,
+		/obj/item/prop/prop_gun,
 		/obj/item/tank/emergency_oxygen,
 		/obj/item/device/flashlight,
 		/obj/item/storage/fancy/cigarettes,

colonialmarines.dme

@@ -970,6 +970,7 @@ s// DM Environment file for colonialmarines.dme.
 #include "code\game\objects\effects\landmarks\structure_spawners\structure_spawner.dm"
 #include "code\game\objects\effects\landmarks\structure_spawners\xvx_hive.dm"
 #include "code\game\objects\effects\spawners\gibspawner.dm"
+#include "code\game\objects\effects\spawners\prop_gun_spawner.dm"
 #include "code\game\objects\effects\spawners\random.dm"
 #include "code\game\objects\effects\spawners\spawner.dm"
 #include "code\game\objects\effects\spawners\vaultspawner.dm"

maps/map_files/USS_Almayer/USS_Almayer.dmm

@@ -69822,12 +69822,7 @@
 	pixel_y = 2
 	},
 /obj/structure/largecrate/random/case,
-/obj/item/prop{
-	desc = "An older design of the Pulse Rifle commonly used by Colonial Marines. This one has seen better days. The trigger is missing, the barrel is bent, and it no longer appropriately feeds magazines.";
-	icon = 'icons/obj/items/weapons/guns/guns_by_faction/uscm.dmi';
-	icon_state = "m41amk1_e";
-	item_state = "m41amk1";
-	name = "\improper Broken M41A pulse rifle";
+/obj/effect/spawner/prop_gun/m41aMK1{
 	pixel_y = 7
 	},
 /obj/item/prop/helmetgarb/gunoil{