[IMP] reactivity: overhaul reactivity system

This commit makes the reactivity system more fine grained and makes it
more eager to stop observing keys or objects when they are modified,
this results in fewer "false positive" notifications.

src/component/component_node.ts

@@ -72,7 +72,9 @@ export function getCurrent(): ComponentNode | null {
 
 type LifecycleHook = Function;
 
-export class ComponentNode<T extends typeof Component = any> implements VNode<ComponentNode> {
+export class ComponentNode<T extends typeof Component = typeof Component>
+  implements VNode<ComponentNode>
+{
   el?: HTMLElement | Text | undefined;
   app: App;
   fiber: Fiber | null = null;