Notable changes:

 * fs: corruption can be caused by fs.writeFileSync() and append-mode
   fs.writeFile() and fs.writeFileSync() under certain circumstances,
   reported in #1058, fixed in #1063 (Olov Lassus).
 * iojs: an "internal modules" API has been introduced to allow core
   code to share JavaScript modules internally only without having to
   expose them as a public API, this feature is for core-only #848
   (Vladimir Kurchatkin).
 * timers: two minor problems with timers have been fixed:
   - Timer#close() is now properly idempotent #1288 (Petka Antonov).
   - setTimeout() will only run the callback once now after an
     unref() during the callback #1231 (Roman Reiss).
 * Windows: a "delay-load hook" has been added for compiled add-ons
   on Windows that should alleviate some of the problems that Windows
   users may be experiencing with add-ons in io.js #1251
   (Bert Belder).
 * V8: minor bug-fix upgrade for V8 to 4.1.0.27.
 * npm: upgrade npm to 2.7.4. See npm CHANGELOG.md for details.