fix(docs): Working generated angular2.d.ts

This requires some hacks, documented in
https://docs.google.com/document/d/1nNebWTiLzz5ePcit_bjZPtaiSIFU4EsQKUlX7LX0c0A/edit

Changes:
- include subtyping info in angular2.d.ts by adding 'extends supertype'
- export missing symbols needed transitively by angular2/angular2
- because of decorator/annotation mismatch, we can't export these to applications.
  So I've added a separate angular2.api.ts file to re-export specifically to .d.ts
  generation.
- Hack to remove aliases introduced by 'import * as alias' syntax
- Hack to deal with Error still an interface

note that we require users to install the transitive dependencies - this is how TSD works.

modules/angular2/angular2.api.dart

@@ -0,0 +1,3 @@
+library angular2.angular2.api;
+// Ignore this file for dart emit.
+// It is used only for generating the TypeScript .d.ts file.

modules/angular2/angular2.api.ts

@@ -0,0 +1,28 @@
+// This module is used by dgeni to produce the angular2.d.ts file.
+
+// Re-export everything we export to the application runtime
+export * from './angular2';
+
+// Horrible hack. See
+// https://docs.google.com/document/d/1nNebWTiLzz5ePcit_bjZPtaiSIFU4EsQKUlX7LX0c0A/edit
+// Exports needed to make angular2.d.ts work,
+// because these symbols are dependencies of other exports but are not otherwise exported.
+// This should be cleaned up in one of two ways:
+// 1) if the symbol is intended to be part of the public API, then re-export somewhere else
+// 2) if the symbol should be omitted from the public API, then the class exposing it should
+//    not be exported, or should avoid exposing the symbol.
+export {AbstractChangeDetector} from './src/change_detection/abstract_change_detector';
+export {ProtoRecord} from './src/change_detection/proto_record';
+export * from './src/core/compiler/element_injector';
+// FIXME: this is a workaround for https://github.com/angular/angular/issues/2356
+// We export the Directive *annotation* instead of the *decorator*.
+// But it breaks the build.
+export {Directive, LifecycleEvent} from './src/core/annotations_impl/annotations';
+export {FormDirective} from './src/forms/directives/form_directive';
+export {ControlContainerDirective} from './src/forms/directives/control_container_directive';
+export {Injectable} from './src/di/annotations_impl';
+export {BaseQueryList} from './src/core/compiler/base_query_list';
+export {AppProtoView, AppView, AppViewContainer} from './src/core/compiler/view';
+export * from './src/change_detection/parser/ast';
+export {Visibility} from './src/core/annotations_impl/visibility';
+export {AppViewManager} from './src/core/compiler/view_manager';