Make Commands and World apis consistent (bevyengine#1703)

Resolves bevyengine#1253 bevyengine#1562

This makes the Commands apis consistent with World apis. This moves to a "type state" pattern (like World) where the "current entity" is stored in an `EntityCommands` builder.

In general this tends to cuts down on indentation and line count. It comes at the cost of needing to type `commands` more and adding more semicolons to terminate expressions.

I also added `spawn_bundle` to Commands because this is a common enough operation that I think its worth providing a shorthand.

crates/bevy_ecs/src/system/exclusive_system.rs

@@ -131,7 +131,7 @@ mod tests {
         ) {
             for entity in query.iter() {
                 *counter += 1;
-                commands.remove::<f32>(entity);
+                commands.entity(entity).remove::<f32>();
             }
         }
 

crates/bevy_gltf/src/loader.rs

@@ -296,18 +296,18 @@ fn load_node(
 ) -> Result<(), GltfError> {
     let transform = gltf_node.transform();
     let mut gltf_error = None;
-    let node = world_builder.spawn((
+    let mut node = world_builder.spawn_bundle((
         Transform::from_matrix(Mat4::from_cols_array_2d(&transform.matrix())),
         GlobalTransform::identity(),
     ));
 
     if let Some(name) = gltf_node.name() {
-        node.with(Name::new(name.to_string()));
+        node.insert(Name::new(name.to_string()));
     }
 
     // create camera node
     if let Some(camera) = gltf_node.camera() {
-        node.with(VisibleEntities {
+        node.insert(VisibleEntities {
             ..Default::default()
         });
 
@@ -325,12 +325,12 @@ fn load_node(
                     ..Default::default()
                 };
 
-                node.with(Camera {
+                node.insert(Camera {
                     name: Some(base::camera::CAMERA_2D.to_owned()),
                     projection_matrix: orthographic_projection.get_projection_matrix(),
                     ..Default::default()
                 });
-                node.with(orthographic_projection);
+                node.insert(orthographic_projection);
             }
             gltf::camera::Projection::Perspective(perspective) => {
                 let mut perspective_projection: PerspectiveProjection = PerspectiveProjection {
@@ -344,12 +344,12 @@ fn load_node(
                 if let Some(aspect_ratio) = perspective.aspect_ratio() {
                     perspective_projection.aspect_ratio = aspect_ratio;
                 }
-                node.with(Camera {
+                node.insert(Camera {
                     name: Some(base::camera::CAMERA_3D.to_owned()),
                     projection_matrix: perspective_projection.get_projection_matrix(),
                     ..Default::default()
                 });
-                node.with(perspective_projection);
+                node.insert(perspective_projection);
             }
         }
     }
@@ -374,7 +374,7 @@ fn load_node(
                 let material_asset_path =
                     AssetPath::new_ref(load_context.path(), Some(&material_label));
 
-                parent.spawn(PbrBundle {
+                parent.spawn_bundle(PbrBundle {
                     mesh: load_context.get_handle(mesh_asset_path),
                     material: load_context.get_handle(material_asset_path),
                     ..Default::default()

crates/bevy_scene/src/command.rs

@@ -20,12 +20,12 @@ impl Command for SpawnScene {
 }
 
 pub trait SpawnSceneCommands {
-    fn spawn_scene(&mut self, scene: Handle<Scene>) -> &mut Self;
+    fn spawn_scene(&mut self, scene: Handle<Scene>);
 }
 
 impl<'a> SpawnSceneCommands for Commands<'a> {
-    fn spawn_scene(&mut self, scene_handle: Handle<Scene>) -> &mut Self {
-        self.add_command(SpawnScene { scene_handle })
+    fn spawn_scene(&mut self, scene_handle: Handle<Scene>) {
+        self.add(SpawnScene { scene_handle });
     }
 }