Add train generation and builder for blueprints

examples/train_blueprint.rs

@@ -0,0 +1,14 @@
+use factorio_blueprint::blueprint::{train::generate_train, BlueprintString};
+
+fn main() {
+    let b = generate_train(2, 4, true, true);
+
+    let b = BlueprintString::Blueprint(b);
+
+    println!("{}", serde_json::to_string_pretty(&b).unwrap());
+
+    println!(
+        "{}",
+        factorio_blueprint::blueprint::encode(&serde_json::to_string(&b).unwrap())
+    );
+}