* This updates all references to nuget.exe to use the copy in the root.
* This deletes all NuGet.config and NuGet.exe files that are not in the root.
* This removes all references to NuGet.targets (which is obsolete and no longer exists)

Move TestUtilities.csproj and TestUtilities.FX45.csproj to separate directories to accomodate current nuget limitations

The targets files were previously split into an open version in
Microsoft.CodeAnalysis.Toolset.Open and a closed version in build/. This
unifies the four targets into two new targets, VSL.Settings.targets and
VSL.Imports.targets, and moves all the targets from ..Toolset.Open into
the build/ folder.

This removes the majority of references to the deprecated Desktop
assemblies.  The only remaining ones are in the VSIX projects.  They
must remain until we actually delete the assemblies.

Upgrades System.Collections.Immutable to 1.1.34-rc and
System.Reflection.Metadata to 1.0.19-rc.

This reverts commit b37052d0.

Preprocessor symbols in VB need to be combined with a comma, not a
semicolon.

The primary use of DefineConstants should be to append constant values,
not replace them.  Any time a replacement operation is used it prevents
us from establishing defines in our targets and pushing them down to all
affected projects.

Bug-1116460 : Renaming the scripting assemblies and namespaces. Making corresponding changes in InstallDogfood and RoslynBuildAndTtest to account for new names (changeset 1408119)

This moves our settings / targets files into the Open directory.  These files are a referenced by virtually all of the projects in the Open directory and are a necessary part of the build process.  Making this change is a necessary step in removing the project scrubber.  (changeset 1396832)

This changes our projects to consume xUnit through NuGet instead of our checked in binaries in Closed\Tools\xUnit.  This is another step in removing project scrubber.  (changeset 1396548)

This changeset introduces the concept of a "global" nuget package. The references to the NuGet packages are inserted into the Open VSL.Settings.targets file, which is imported into every project in Roslyn. This ensures that every project automatically gets these "global" packages. (changeset 1386548)

Updates System.Collections.Immutable and System.Metadata.Reader to versions 1.1.33-beta and 1.0.18-beta, respectively.
     Updates VSMEF to the latest build from VSPRO_1.

     A few code fixes:
     - ImmutableArrayInterop is gone
       - in product we used in a couple of places where we now just create a copy of the byte[] (MetadataWriter)
       - test infrastructure uses a workaround with explicitly laid out union to avoid copies of large metadata blobs
     - EditorTestApp class was incorrectly importing MEF components resulting in a cycle. The new VSMEF reports such errors. (changeset 1385613)

***NO_CI***
 (changeset 1356181)

This also updates Microsoft.Net.ToolsetCompiler to the corresponding version. (changeset 1355122)

When our projects were last updated to a newer version of Microsoft.Net.ToolsetCompilers, NuGet didn't replace the old version--it just put the new version next to it. Every project ended up referencing both versions, and which set of compiler binaries "won" depended on the order they appeared in the project file. So different projects built with different compilers.

This change strips out all references to the old version. (changeset 1352054)

Current approach and issues

     When emitting method body of a method updated during EnC the compiler needs to assign local variables the same slots they had before the edit, so that state stored in those locals gets preserved.
     To implement this slot mapping we used to encode information into synthesized variable names that identified the syntax node that produced the variable and ultimately allowed us to calculate the slot mapping.
     For user variables we identified the slot by name. In both cases we relied on an assumption that the compiler assigns slots in syntax order. This assumption is false in some cases. We could make it true but the requirement would be fragile and hard to enforce when new features are implemented in the compiler since the entire lowering pipeline would need to preserve the assumption.

     New approach
     In the new approach we calculate a "syntax offset" for each user-defined and long-lived synthesized variable. Every such variable symbol has to be associated with a syntax node (its declarator). In usual cases this is the textual distance of the declarator from the start of the method body. It gets a bit complicated when the containing method body is not contiguous (constructors). If the variable is in the body of the constructor the definition of syntax offset is the same. If the variable is defined in a constructor  initializer or in a member initializer (this is only possible when declaration expressions or closures in primary constructors are involved) then the distance is a negative sum of the widths of all the initializers that succeed the declarator of the variable in the emitted constructor body plus the relative offset of the declarator from the start of the containing initializer.

     If a single node is a declarator for multiple variables of the same synthesized kind (it can only happen for synthesized variables) we calculate additional number "ordinal" for such variable. We assign the ordinals to the synthesized variables with the same kind and syntax offset in the order as they appear in the lowered bound tree. It is important that a valid EnC edit can't change the ordinal of a synthesized variable. If it could it would need to be assigned a different kind or associated with a different declarator node.

     To support EnC of async method we will assign another number "subordinal" to certain synthesized locals (produced by spilling by-ref variables) to simplify the mapping. Assigning of such number is not yet implemented in this change.

     Together (syntax offset, ordinal, subordinal) form a LocalDebugId of a variable. Since this id needs to be stored in PDB for both user-defined and long-lived synthesized variables we can’t encode it in the name of the variable (the names of user-defined variables have to be their user specified names). Therefore this change introduces a new custom debug info record that is associated with a method. The record encodes the kind and id for each local slot of the method.

     As a consequence we no longer emit names for synthesized long-lived variables (“CS$...”) unless it’s necessary for backward comp with Dev12 EE (only display class local names need to be emitted for this reason). (changeset 1348066)

***NO_CI***
 (changeset 1341082)

Removes workarounds for portability bugs 967430 and 797360 - the underlying issues in the project system have been fixed.
Removes explicit references to portable facade assemblies (System.IO, System.Runtime, etc.).
 (changeset 1336570)

Update the version of the toolset compilers used for build and make sure that all projects are using the toolset NuGet. (changeset 1330804)

Removes UnoptimizedDll/unoptimizedExe and other /optimize & /debug option combinations from tests.
Fixes bug in C# EE - we have incorrectly treated end offset of a local scope as inclusive. It's exclusive for C#, inclusive for VB. (changeset 1313100)

Splits Microsoft.CodeAnalysis, Microsoft.CodeAnalysis.CSharp and Microsoft.CodeAnalysis.VisualBasic into portable and desktop assemblies.

Existing Core\Source, CSharp\Source and VisualBasic\Source directories are renamed to Core\Portable, CSharp\Portable and VisualBasic\Portable.
New sibling Desktop folders are added and non-portable source is moved there.
"System.Runtime" references has to be removed in order for the portable project system magic to automatically add facade references.
 (changeset 1281686)

Add IVT for VB EE (ResultProvider) and change .targets so we don't "Import System.Linq" in projects that target .NET 2.0. (changeset 1274168)

     Expression Evaluator Restructuring

 Change Description:

     Rename assemblies, namespaces, and folders

     Microsoft.CodeAnalysis.ExpressionEvaluator.ExpressionCompiler.dll
     [Shared ResultProvider dll not yet created]
     Microsoft.CodeAnalysis.CSharp.ExpressionEvaluator.ExpressionCompiler.dll
     Microsoft.CodeAnalysis.CSharp.ExpressionEvaluator.ResultProvider.dll
     Microsoft.CodeAnalysis.VisualBasic.ExpressionEvaluator.ExpressionCompiler.dll
     [VB ResultProvider dll not yet created]
     Roslyn.ExpressionEvaluator.CSharp.ExpressionCompiler.dll
     Roslyn.ExpressionEvaluator.VisualBasic.ExpressionCompiler.dll
     Roslyn.ExpressionEvaluator.CSharp.ResultProvider.dll
     [VB ResultProvider test dll not yet created]

TODO: Address CR feedback separately. (changeset 1272594)