First sound! Added ship explosion sound effect

It's a simple one-shot sound clip that gets dispatched as one more part
of the ship impact routine.

The GameAssets struct has been updated to have an array of handles for
audio assets (just the one, for now).

This sound file, and the next several, are all from Kenney
(www.kenney.nl).

src/resources.rs

@@ -1,7 +1,8 @@
 //! All the resources for the game
 
 use bevy::{
-    asset::{Assets, Handle},
+    asset::{AssetServer, Assets, Handle},
+    audio::AudioSource,
     ecs::{
         resource::Resource,
         world::{FromWorld, World},
@@ -57,6 +58,7 @@ impl Default for WorldSize {
 pub struct GameAssets {
     meshes: [Handle<Mesh>; 5],
     materials: [Handle<ColorMaterial>; 7],
+    sounds: [Handle<AudioSource>; 1],
 }
 
 impl GameAssets {
@@ -95,6 +97,10 @@ impl GameAssets {
     pub fn bullet(&self) -> (Handle<Mesh>, Handle<ColorMaterial>) {
         (self.meshes[4].clone(), self.materials[6].clone())
     }
+
+    pub fn wreck_sound(&self) -> Handle<AudioSource> {
+        self.sounds[0].clone()
+    }
 }
 
 impl FromWorld for GameAssets {
@@ -122,6 +128,12 @@ impl FromWorld for GameAssets {
             world_materials.add(ASTEROID_SMALL_COLOR),
             world_materials.add(BULLET_COLOR),
         ];
-        GameAssets { meshes, materials }
+        let loader = world.resource_mut::<AssetServer>();
+        let sounds = [loader.load("explosionCrunch_004.ogg")];
+        GameAssets {
+            meshes,
+            materials,
+            sounds,
+        }
     }
 }