Fixed a bug that caused the Interval and Timer extensions and periodic scheduling in general to throw an ArgumentOutOfRangeException when period equaled TimeSpan.Zero.  Includes corresponding unit tests.
Merge branch 'master' of https://git01.codeplex.com/forks/davedev/rxperiodzero into develop

Fixed a bug that caused the Interval and Timer extensions and periodic scheduling in general to throw an ArgumentOutOfRangeException when period equaled TimeSpan.Zero. Includes corresponding unit tests.
SelectMany overloads with index parameter in selector functions.
Added GroupBy and GroupByUntil overloads with a capacity parameter.
Added missing using statements.
Added missing using statement to unit test.
Ran HomoIcon tool.
Merged with latest changes in CodePlex.
Added the BehaviorSubject<T>.Value property, which extracts the current value.
Implemented OrderBy, OrderByDescending, ThenBy and ThenByDescending, with unit tests.  This also required me to update to the HomoIcon tool and the Qbservable parity unit test.
Rename Ix/NET/** to Ix.NET/**. Rename Rx/NET/** to Rx.NET/**
Rename Rx/NET directory to Rx.NET
Add [SecurityCritical] attribute to IYielder.UnsafeOnCompleted
Fix test that fails because of additional IEnumerable.Create method
Refactoring build files, part one
Update Ix .csproj files and .targets files, mostly cleanup
Add "Layout" subfolders to .gitignore
Re-add "References" folder to Ix
Update readme.md
Update readme.md