[DOC] add hooks explanation, and testing/debug page

closes #372
closes #419

src/context.ts

@@ -139,10 +139,10 @@ export function useContextWithCB(ctx: Context, component: Component<any, any>, m
     }
   });
   const __destroy = component.__destroy;
-  component.__destroy = (parent) => {
+  component.__destroy = parent => {
     ctx.off("update", component);
     delete mapping[id];
     __destroy.call(component, parent);
-  }
+  };
   return ctx.state;
 }

src/qweb/qweb.ts

@@ -460,8 +460,10 @@ export class QWeb extends EventBus {
       // this is a component, we modify in place the xml document to change
       // <SomeComponent ... /> to <t t-component="SomeComponent" ... />
       node.setAttribute("t-component", node.tagName);
-    } else if (node.tagName !== 't' && node.hasAttribute('t-component')) {
-      throw new Error(`Directive 't-component' can only be used on <t> nodes (used on a <${node.tagName}>)`);
+    } else if (node.tagName !== "t" && node.hasAttribute("t-component")) {
+      throw new Error(
+        `Directive 't-component' can only be used on <t> nodes (used on a <${node.tagName}>)`
+      );
     }
     const attributes = (<Element>node).attributes;