Merge pull request #134 from bikal/master

Fixed issue #133
Integrate updates from Visual F# team for Visual Studio 2012 Update 2
Integrate changes from Microsoft Visual F# source code drop http://fsharppowerpack.codeplex.com up to change 71609, including changes for VS2012 Update 2 - Portable Async and Query fixes
Minor textual changes to align fsharp/fsharp with fsharppowerpack.codeplex.com
Merge branch 'extend' of git://github.com/dungpa/fsharp
Update README.md

Added description of forks intended use.
Merge branch 'master' of https://github.com/dungpa/fsharp