Adds Barsign Picking

This commit allows the bartender, or anyone with access_bar, to change the
barsign's image by hitting it with an ID. This commit also adds a variable
to disable such behavior for custom maps. Finally, this commit adds two
new icons for the barsign, named simply 'on' and 'off', which look like
the base sprite for most of the other barsigns, but blank.

code/game/objects/structures/barsign.dm

@@ -2,6 +2,7 @@
 	icon = 'icons/obj/barsigns.dmi'
 	icon_state = "empty"
 	anchored = 1
+	var/nopick = 0
 	New()
 		ChangeSign(pick("magmasea", "limbo", "rustyaxe", "armokbar", "brokendrum", "meadbay", "thecavern", "cindikate", "theorchard", "lv426", "zocalo", "4theemprah", "ishimura", "tardis", "quarks", "tenforward", "thepranicngpony", "vault13", "solaris", "thehive", "cantina", "theouterspess", "milliways42", "thetimeofeve", "spaceasshole", "dwarffortress", "thebark", "thedrunkcarp", "theharmbaton", "thenest", "officerbeersky", "thesingulo"))
 		return
@@ -10,3 +11,18 @@
 		//on = 0
 		//brightness_on = 4 //uncomment these when the lighting fixes get in
 		return
+
+/obj/structure/sign/double/barsign/attackby(obj/item/I, mob/user)
+	if(nopick)
+		return
+
+	if(istype(I, /obj/item/weapon/card/id))
+		var/obj/item/weapon/card/id/card = I
+		if(access_bar in card.GetAccess())
+			var/sign_type = input(user, "What would you like to change the barsign to?") as null|anything in list("Off", "Magma Sea", "Limbo", "Rusty Axe", "Armok Bar", "Broken Drum", "Mead bay", "The Cavern", "Cindi Kate", "The Orchard", "LV 426", "Zocalo", "4 The Emprah", "Ishimura", "Tardis", "Quarks", "Ten Forward", "The Pranicng Pony", "Vault 13", "Solaris", "The Hive", "Cantina", "The Outer Spess", "Milliways 42", "The Time Of Eve", "Space Asshole", "Dwarf Fortress", "The Bark", "The Drunk Carp", "The Harm Baton", "The Nest", "Officer Beersky", "The Singulo", "On")
+			if(sign_type == null)
+				return
+			else
+				sign_type = replacetext(lowertext(sign_type), " ", "") // lowercase, strip spaces - along with choices for user options, avoids huge if-else-else
+				src.ChangeSign(sign_type)
+				user << "You change the barsign."