Upgrade tests to use Xunit 2.0
Fix DEBUG constant name
Fix some more XML docs
Improve Dictionary access
Remove app.config from Registry.
Merge pull request #254 from alfaproject/regex_dictionary

Improve Dictionary access
Prepare metadata reader tests to be portable
Build metadata reader tests as PCL
Re-enable some Vector tests which were flaky on CI machines
Merge pull request #259 from Priya91/registry

Remove app.config from Registry.
Merge pull request #263 from mellinoe/enable-vector-tests

Re-enable some Vector tests which were flaky on CI machines
Optimize ternary condition return
Merge pull request #268 from alfaproject/regex_ccek_equals

Clean up a line to avoid a ternary operator
Add System.IO.Pipes source code
Merge branch 'xunit2' into test_on_coreclr

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
	src/System.Numerics.Vectors/tests/Vector2Tests.cs
	src/System.Numerics.Vectors/tests/Vector4Tests.cs
	src/System.Reflection.Metadata/tests/TestUtilities/WorkItemAttribute.cs
Merge branch 'mdreader-portable-tests' into test_on_coreclr

Conflicts:
	src/System.Reflection.Metadata/tests/Metadata/MetadataReaderTests.cs
	src/System.Reflection.Metadata/tests/System.Reflection.Metadata.Tests.csproj
	src/System.Reflection.Metadata/tests/packages.config
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.
Update XML tests to register a code page provider

Required for the tests to pass on .NET Core.
Improve ActionBlock.Post perf for SingleProducerConstrained