Implement land, terrain, environment, and sound managers (#70)

tests/compat/tests/world_manager_shims.rs

@@ -81,8 +81,7 @@ fn world_facing_constructors_preserve_implemented_and_pending_behavior() {
     assert!(parcel.always_request_acl);
     assert!(parcel.always_request_dwell);
     assert!(!parcel.pool_parcel_data);
-    assert_eq!(
-        member_id(TerrainPatch::new()),
-        "M:LibreMetaverse.TerrainPatch.#ctor"
-    );
+    let terrain = TerrainPatch::new().expect("TerrainPatch constructor");
+    assert!(terrain.data.is_empty());
+    assert_eq!((terrain.x, terrain.y), (0, 0));
 }