pkg/utf: fixed layout, added todos, updated docs and homepage pubspec links

pkg/utf/test/utf16_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-library utf16_tests;
+library utf.utf16_test;
+
 import 'package:expect/expect.dart';
 import 'package:utf/utf.dart';
 
 const String testKoreanCharSubset = """
 가각갂갃간갅갆갇갈갉갊갋갌갍갎갏감갑값갓갔강갖갗갘같갚갛
 개객갞갟갠갡갢갣갤갥갦갧갨갩갪갫갬갭갮갯갰갱갲갳갴갵갶갷
 갸갹갺갻갼갽갾갿걀걁걂걃걄걅걆걇걈걉걊걋걌걍걎걏걐걑걒걓""";
 
 const String testHanWater = "水";
 
@@ skipping 102 matching lines @@
   // specify types
   Expect.equals(44032, (new List<int>
       .from(decodeUtf16beAsIterable(testKoreanCharSubsetUtf16beBom)))[0]);
   Expect.equals(44032, (new List<int>
       .from(decodeUtf16leAsIterable(testKoreanCharSubsetUtf16le)))[0]);
   bool stripBom = false;
   Expect.equals(UNICODE_BOM, (new List<int>
       .from(decodeUtf16beAsIterable(testKoreanCharSubsetUtf16beBom,
             0, null, stripBom)))[0]);
 }