wip: more progress on parity docs.

Placeholders in the rsx macro for future features.

packages/core/src/diff.rs

@@ -41,11 +41,9 @@ use std::{
     cell::{RefCell, RefMut},
     cmp::Ordering,
     collections::VecDeque,
+    rc::{Rc, Weak},
     sync::atomic::AtomicU32,
-    // rc::{Rc, Weak},
-    sync::{Arc, Weak},
 };
-type Rc<T> = Arc<T>;
 
 /// The DiffState is a cursor internal to the VirtualDOM's diffing algorithm that allows persistence of state while
 /// diffing trees of components. This means we can "re-enter" a subtree of a component by queuing a "NeedToDiff" event.