Add System.IO.Pipes source code
Merge pull request #269 from mellinoe/add-pipes

Add System.IO.Pipes source code
Updated Readme to include Pipes

Added a short description of System.IO.Pipes to the readme list.
Improve ActionBlock.Post perf for SingleProducerConstrained
Make SpscTargetCore.OfferMessage use Post method on fast path
Remove TargetCore.Post method as it doesn't add to perf.
Revert "Formatting changes to private fields."

This reverts commit 9073ca9794cc5c59d5535267aa00cd247dce8f97.

Conflicts:
	src/System.Numerics.Vectors/tests/Matrix3x2Tests.cs
	src/System.Numerics.Vectors/tests/Matrix4x4Tests.cs
	src/System.Numerics.Vectors/tests/PlaneTests.cs
	src/System.Numerics.Vectors/tests/QuaternionTests.cs
Add System.Diagnostics.FileVersionInfo source
Formatting changes to System.Collections.Immutable
Formatting changes to Numerics
Merge pull request #275 from Priya91/formatting

Formatting changes to System.Collections.Immutable
Remove  whitespace  left after previous commit.
Merge pull request #248 from omariom/ActionBlockPerfEnhancements

Perf improvement for ActionBlock.Post when SingleProducerConstrained == true
Merge pull request #276 from Priya91/formatting-numerics

Formatting changes to Numerics
Merge pull request #274 from mellinoe/add-fvi

Add System.Diagnostics.FileVersionInfo source
Add FileVersionInfo to the readme

And add a short description of the library.