Make the ExtensionSet constructor public (#187)

Make the ExtensionSet constructor public; bump to 1.1.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b4b93de..34ef832 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 1.1.0
+
+* Make the constructor for ExtensionSet public, for tools like dartdoc.
+
 ## 1.0.0
 
 * Fix issue where `accept` could cause an exception.
diff --git a/README.md b/README.md
index 22ddb3f..9970e28 100644
--- a/README.md
+++ b/README.md
@@ -73,10 +73,6 @@
 
   * `new InlineHtmlSyntax()`
   * `const FencedCodeBlockSyntax()`
-  * `const HeaderWithIdSyntax()`, which adds `id` attributes to ATX-style
-    headers, for easy intra-document linking.
-  * `const SetextHeaderWithIdSyntax()`, which adds `id` attributes to
-    Setext-style headers, for easy intra-document linking.
   * `const TableSyntax()`
 
 ### Custom syntax extensions
diff --git a/lib/src/extension_set.dart b/lib/src/extension_set.dart
index cb381de..863004f 100644
--- a/lib/src/extension_set.dart
+++ b/lib/src/extension_set.dart
@@ -1,18 +1,23 @@
 import 'block_parser.dart';
 import 'inline_parser.dart';
 
+/// ExtensionSets provide a simple grouping mechanism for common Markdown
+/// flavors.
+///
+/// For example, the [gitHub] set of syntax extensions allows users to output
+/// HTML from their Markdown in a similar fashion to GitHub's parsing.
 class ExtensionSet {
-  static final ExtensionSet none = new ExtensionSet._([], []);
+  static final ExtensionSet none = new ExtensionSet([], []);
 
-  static final ExtensionSet commonMark = new ExtensionSet._(
+  static final ExtensionSet commonMark = new ExtensionSet(
       [const FencedCodeBlockSyntax()], [new InlineHtmlSyntax()]);
 
-  static final ExtensionSet gitHub = new ExtensionSet._(
+  static final ExtensionSet gitHub = new ExtensionSet(
       [const FencedCodeBlockSyntax(), const TableSyntax()],
       [new InlineHtmlSyntax()]);
 
   final List<BlockSyntax> blockSyntaxes;
   final List<InlineSyntax> inlineSyntaxes;
 
-  ExtensionSet._(this.blockSyntaxes, this.inlineSyntaxes);
+  ExtensionSet(this.blockSyntaxes, this.inlineSyntaxes);
 }
diff --git a/lib/src/version.dart b/lib/src/version.dart
index bbc1fff..5d1894e 100644
--- a/lib/src/version.dart
+++ b/lib/src/version.dart
@@ -1,2 +1,2 @@
 /// The current version of markdown.
-final String version = '1.0.0';
+final String version = '1.1.0';
diff --git a/pubspec.yaml b/pubspec.yaml
index 93ca5ba..f260848 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: markdown
-version: 1.0.0
+version: 1.1.0
 author: Dart Team <misc@dartlang.org>
 description: A library for converting markdown to HTML.
 homepage: https://github.com/dart-lang/markdown