allow public uses of structs; add sample program

src/item.rs

@@ -2,10 +2,10 @@ use crate::{AnimationFrames, Image, mock};
 
 #[derive(Debug, Eq, PartialEq)]
 pub struct Item {
-    pub(crate) id: String,
-    pub(crate) animation_frames: Vec<Image>,
-    pub(crate) name: Option<String>,
-    pub(crate) dialogue: Option<String>, // dialogue id
+    pub id: String,
+    pub animation_frames: Vec<Image>,
+    pub name: Option<String>,
+    pub dialogue: Option<String>, // dialogue id
 }
 
 impl From<String> for Item {