refactor(Lifecycle hooks): move the hooks to their own module (lifecycle_hooks)

BREAKING CHANGE

Lifecycle hooks now live in the `angular2/lifecycle_hooks` module.
They previously lived in the `metadata` module.

modules/angular2/src/core/compiler/directive_lifecycle_reflector.dart

@@ -2,7 +2,7 @@ library angular2.src.core.compiler.directive_lifecycle_reflector;
 
 import 'package:angular2/src/core/reflection/reflection.dart';
 
-bool hasLifecycleHook(/*LifecycleHook*/ interface, type) {
+bool hasLifecycleHook(interface, type) {
   if (type is! Type) return false;
 
   return reflector.interfaces(type).contains(interface);

modules/angular2/src/core/compiler/directive_lifecycle_reflector.ts

@@ -1,7 +1,7 @@
 import {Type} from 'angular2/src/core/facade/lang';
 import * as Interfaces from './interfaces';
 
-export function hasLifecycleHook(lcInterface: Interfaces.LifecycleHook, type): boolean {
+export function hasLifecycleHook(lcInterface, type): boolean {
   if (!(type instanceof Type)) return false;
 
   var proto = (<any>type).prototype;

modules/angular2/src/core/compiler/interfaces.ts

@@ -8,10 +8,7 @@ import {StringMap} from 'angular2/src/core/facade/collection';
  * - `AfterContentInit`,
  * - `AfterContentChecked`,
  * - `OnDestroy` (at the very end before destruction)
- *
- * // todo(vicb): describe Dart & TS vs JS
  */
-export interface LifecycleHook {}
 
 /**
  * Notify a directive when any of its bindings have changed.
@@ -41,7 +38,7 @@ export interface LifecycleHook {}
  * }
  *  ```
  */
-export class OnChanges implements LifecycleHook {
+export class OnChanges {
   onChanges(changes: StringMap<string, any>): void {}
 }
 
@@ -63,7 +60,7 @@ export class OnChanges implements LifecycleHook {
  * }
  *  ```
  */
-export class OnInit implements LifecycleHook {
+export class OnInit {
   onInit(): void {}
 }
 
@@ -86,7 +83,7 @@ export class OnInit implements LifecycleHook {
  * }
  *  ```
  */
-export class DoCheck implements LifecycleHook {
+export class DoCheck {
   doCheck(): void {}
 }
 
@@ -104,7 +101,7 @@ export class DoCheck implements LifecycleHook {
  * }
  * ```
  */
-export class OnDestroy implements LifecycleHook {
+export class OnDestroy {
   onDestroy(): void {}
 }
 
@@ -122,7 +119,7 @@ export class OnDestroy implements LifecycleHook {
  * }
  *  ```
  */
-export class AfterContentInit implements LifecycleHook {
+export class AfterContentInit {
   afterContentInit(): void {}
 }
 
@@ -140,7 +137,7 @@ export class AfterContentInit implements LifecycleHook {
  * }
  *  ```
  */
-export class AfterContentChecked implements LifecycleHook {
+export class AfterContentChecked {
   afterContentChecked(): void {}
 }
 
@@ -158,7 +155,7 @@ export class AfterContentChecked implements LifecycleHook {
  * }
  *  ```
  */
-export class AfterViewInit implements LifecycleHook {
+export class AfterViewInit {
   afterViewInit(): void {}
 }
 
@@ -176,6 +173,6 @@ export class AfterViewInit implements LifecycleHook {
  * }
  *  ```
  */
-export class AfterViewChecked implements LifecycleHook {
+export class AfterViewChecked {
   afterViewChecked(): void {}
 }

modules/angular2/src/core/directives/ng_class.ts

@@ -1,5 +1,6 @@
 import {isPresent, isString, StringWrapper, isBlank} from 'angular2/src/core/facade/lang';
-import {Directive, DoCheck, OnDestroy} from 'angular2/metadata';
+import {Directive} from 'angular2/metadata';
+import {DoCheck, OnDestroy} from 'angular2/lifecycle_hooks';
 import {ElementRef} from 'angular2/core';
 import {Renderer} from 'angular2/src/core/render/api';
 import {

modules/angular2/src/core/directives/ng_for.ts

@@ -1,4 +1,5 @@
-import {Directive, DoCheck} from 'angular2/metadata';
+import {Directive} from 'angular2/metadata';
+import {DoCheck} from 'angular2/lifecycle_hooks';
 import {ViewContainerRef, ViewRef, TemplateRef} from 'angular2/core';
 import {ChangeDetectorRef, IterableDiffer, IterableDiffers} from 'angular2/change_detection';
 import {isPresent, isBlank} from 'angular2/src/core/facade/lang';

modules/angular2/src/core/directives/ng_style.ts

@@ -1,4 +1,5 @@
-import {Directive, DoCheck} from 'angular2/metadata';
+import {Directive} from 'angular2/metadata';
+import {DoCheck} from 'angular2/lifecycle_hooks';
 import {ElementRef} from 'angular2/core';
 import {KeyValueDiffer, KeyValueDiffers} from 'angular2/change_detection';
 import {isPresent, isBlank, print} from 'angular2/src/core/facade/lang';

modules/angular2/src/core/metadata/directives.ts

@@ -318,6 +318,10 @@ import {ChangeDetectionStrategy} from 'angular2/change_detection';
  * the directive
  * controller is correctly instantiated on the `<template>` element rather than the `<li>` element.
  *
+ * ## Lifecycle hooks
+ *
+ * When the directive class implements some {@link angular2/lifecycle_hooks} the callbacks are
+ * called by the change detection at defined points in time during the life of the directive.
  *
  * ## Example
  *
@@ -734,6 +738,11 @@ export class DirectiveMetadata extends InjectableMetadata {
  *
  * For details on the `@View` annotation, see {@link ViewMetadata}.
  *
+ * ## Lifecycle hooks
+ *
+ * When the component class implements some {@link angular2/lifecycle_hooks} the callbacks are
+ * called by the change detection at defined points in time during the life of the component.
+ *
  * ## Example
  *
  * ```