Synchronize Trenchbroom map entities (#65)

crates/shared/src/aim/mod.rs

@@ -79,14 +79,13 @@ fn update_player_aim(
     spatial_query: SpatialQuery,
 ) {
     for (player, state, mut aim_target, children) in player_aim.iter_mut() {
-        assert_eq!(
-            children.len(),
-            1,
-            "expected player to have one direct child"
-        );
+        let player_rot_child = children
+            .iter()
+            .find(|&child| player_rot.contains(child))
+            .expect("expected child with PlayerBodyMesh");
 
         let (player_pos, player_forward) = player_rot
-            .get(*children.first().unwrap())
+            .get(player_rot_child)
             .map(|(t, global)| (global.translation(), t.forward()))
             .unwrap();