sprites for entities, with text glyph fallback

src/raws/item_structs.rs

@@ -30,7 +30,8 @@ pub struct Equippable {
 #[derive(Deserialize, Debug)]
 pub struct Renderable {
     pub glyph: String,
-    pub sprite: Option<usize>,
+    pub sprite: Option<String>,
+    pub colour_sprite: Option<bool>,
     pub fg: String,
     pub bg: String,
     pub order: i32,