Subtree memorization / reactive templates (#488)

This commit adds subtree memoization to Dioxus.

Subtree memoization is basically a compile-time step that drastically 
reduces the amount of work the diffing engine needs to do at runtime by
extracting non-changing nodes out into a static "template." Templates 
are then understood by the various renderers in the ecosystem as a 
faster way of rendering the same items. 

For example, in the web, templates are simply a set of DOM Nodes created 
once and then cloned later. This is the same pattern frameworks like Lithtml
and SolidJS use to achieve near-perfect performance. 

Subtree memoization adds an additional level of complexity to Dioxus. The RSX
macro needs to be much smarter to identify changing/nonchanging nodes and
generate a mapping between the Template and its runtime counterparts.

This commit represents a working starter point for this work, adding support 
for templates for the web, desktop, liveview, ssr, and native-core renderers.
In the future we will try to shrink code generation, generally improve 
performance, and simplify our implementation.

packages/tui/src/lib.rs

@@ -94,7 +94,7 @@ pub fn launch_cfg(app: Component<()>, cfg: Config) {
         let to_update = rdom.apply_mutations(vec![mutations]);
         let mut any_map = AnyMap::new();
         any_map.insert(taffy.clone());
-        let _to_rerender = rdom.update_state(&dom, to_update, any_map);
+        let _to_rerender = rdom.update_state(to_update, any_map);
     }
 
     render_vdom(
@@ -133,8 +133,10 @@ fn render_vdom(
                 terminal.clear().unwrap();
             }
 
-            let mut to_rerender: fxhash::FxHashSet<ElementId> =
-                vec![ElementId(0)].into_iter().collect();
+            let mut to_rerender: fxhash::FxHashSet<GlobalNodeId> =
+                vec![GlobalNodeId::VNodeId(ElementId(0))]
+                    .into_iter()
+                    .collect();
             let mut updated = true;
 
             loop {
@@ -250,7 +252,7 @@ fn render_vdom(
                     // update the style and layout
                     let mut any_map = AnyMap::new();
                     any_map.insert(taffy.clone());
-                    to_rerender = rdom.update_state(vdom, to_update, any_map);
+                    to_rerender = rdom.update_state(to_update, any_map);
                 }
             }