chore(doc-gen): put typescript stuff into its own package

This means that we can now run just the d.ts file generation by running:

```bash
gulp docs/typings
```

In addition the type definition generation was messing with the other docs tasks
so separating it also fixes problems there.

docs/typescript-definition-package/templates/angular2/angular2.d.ts.template.html

@@ -0,0 +1,32 @@
+{% extends '../type-definition.template.html' %}
+{% block staticDeclarations %}
+// Angular depends transitively on these libraries.
+// If you don't have them installed you can run
+// $ tsd query es6-promise rx rx-lite --action install --save
+///<reference path="../es6-promise/es6-promise.d.ts"/>
+///<reference path="../rx/rx.d.ts"/>
+
+interface List<T> extends Array<T> {}
+interface Map<K,V> {}
+interface StringMap<K,V> extends Map<K,V> {}
+
+declare module ng {
+  type SetterFn = typeof Function;
+  type int = number;
+  interface Type extends Function {
+    new (...args);
+  }
+
+  // See https://github.com/Microsoft/TypeScript/issues/1168
+  class BaseException /* extends Error */ {
+    message: string;
+    stack: string;
+    toString(): string;
+  }
+  interface InjectableReference {}
+}
+{% endblock %}
+
+declare module "angular2/angular2" {
+  export = ng;
+}

docs/typescript-definition-package/templates/type-definition.template.html

@@ -0,0 +1,72 @@
+
+{%- macro commentBlock(doc, level) -%}
+{%- if doc.content | trim %}
+
+{% if level > 1 %}{$ '/**' | indent(level-1, true) | replace(r/\n$/, "") $}{% else %}/**{% endif %}
+{$ doc.content | trim | replace(r/^/gm, "* ") | indent(level, true) | replace(r/\n$/, "") $}
+{$ '*/' | indent(level, true) | replace(r/\n$/, "") $}{% endif -%}
+{%- endmacro -%}
+
+
+{%- macro memberInfo(member) -%}
+{$ commentBlock(member, 5) $}
+     {$ member.name $}{% if member.optional %}?{% endif -%}
+{% if member.typeParameters %}<{% for typeParam in member.typeParameters %}{$ typeParam $}{% if not loop.last %}, {% endif %}{% endfor %}>{% endif -%}
+{%- if member.parameters -%}({% for param in member.parameters %}{$ param $}{% if not loop.last %}, {% endif %}{% endfor %}){%- endif -%}
+{%- if member.returnType == 'Directive' %}: DirectiveAnnotation{%- elif member.returnType -%}: {$ member.returnType $}{%- else -%}: void
+{%- endif -%};
+{%- endmacro -%}
+
+
+// Type definitions for Angular v{$ versionInfo.currentVersion.full | replace(r/\+/, "_") $}
+// Project: http://angular.io/
+// Definitions by: angular team <https://github.com/angular/>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+// ***********************************************************
+// This file is generated by the Angular build process.
+// Please do not create manual edits or send pull requests
+// modifying this file.
+// ***********************************************************
+{% block staticDeclarations %}{% endblock %}
+{% for alias, module in doc.moduleDocs %}
+{$ commentBlock(module.doc, 1) $}
+declare module ng {
+
+  {%- for export in module.doc.exports -%}
+  {%- if export.content -%}
+    {$ commentBlock(export, 3) $}
+  {%- endif %}
+  {$ export.docType $} {$ export.name $}{$ export.typeParams $}{%- if export.heritage == ' extends Directive' %} extends DirectiveAnnotation{% else %}{$ export.heritage $}{% endif %}
+  {%- if export.docType == 'class' or export.docType == 'interface' %} {
+  {%- if export.newMember %}
+    {$ memberInfo(export.newMember) $}
+  {% endif %}
+  {%- if export.callMember %}
+    {$ memberInfo(export.callMember) $}
+  {% endif -%}
+  {%- for member in export.members %}
+    {$ memberInfo(member) $}
+  {%- endfor %}
+  }
+
+  {%- elif export.docType == 'enum' %} {
+    {%- for member in export.members %}
+    {$ member $}{% if not loop.last %},
+    {%- endif -%}
+    {%- endfor %}
+  }
+
+  {%- else -%}
+    {% if export.parameters %}({% for param in export.parameters %}{$ param $}{% if not loop.last %}, {% endif %}{% endfor %}){%- endif %}
+    {%- if export.returnType %} : {$ export.returnType $} {% endif -%}
+    ;
+  {%- endif %}
+  {% endfor %}
+}
+
+{% endfor %}
+
+declare module "angular2/angular2" {
+  export = ng;
+}