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
Merge branch 'master' into develop