added instances function to root_config

src/types/root_config.rs

@@ -95,6 +95,10 @@ impl RootConfig {
         self.mods.insert(new_mod.id().to_owned(), new_mod.clone());
     }
 
+    pub fn instances(&self) -> Vec<String> {
+        self.instances.keys().cloned().collect()
+    }
+
     pub fn load_instance_by_id(&self, id: &str) -> Result<ModdedInstance, ConfigReadWriteError> {
         debug!("Loading instance {}", id);
         let conf = self