Most interesting parts here are:
* the syntax node shape and naming - these are public APIs so we should get the naming right.
NOTE: I expect some churn here so for now I have disabled the public API diagnostics.

* parsing something that starts with "("  is tricky since that can be a start of many constructs - lambdas, casts, parenthesized expressions...
I have updated the lookahead logic that tries to figure what we are dealing with, but it may need some tuning to be more robust.
In particular there could be some error recovery work to see that handling of broken code is sensible.

==== Current assumptions:
1) TupleTypes and TupleExpressions must have 2 or more elements/arguments. However we may have to parse 0 and 1 sized expressions for error recovery reasons. Those are syntax errors.

2) TupleType looks like

(int x, int y)  x = ...

I.E.

  ( type [name], type [name])

We may enforce that all or no elements have names. Not sure yet if that needs to be in parser or binder.

3) TupleExpression looks like

var something = (x: foo(), y: bar);

I.E.

  ( [name:] expr, [name:] expr)

just like with the types we may want to enforce that all or none of the arguments have names. Not sure if that is a syntax or binding error.
It is not a part of this change.

Local function testing: var and async

Merge "typeswitch" into future

Remove evidence of advanced pattern-matching features for C# 7.

Address netstandard1.3 warnings

Clean up PortablePdb shims

Replace usages of CopyReferencesByDefault/CopyNuGetImplementations

Merge master into future

Replaced usages of these build properties with UseCommonOutputDirectory, which is a built-in concept.

This enables us to share output directory, and a few other properties needed for VS15 conversion.

Move DeployTestDependencies to use same targets as Dependencies

This lets us stop calling csc.exe for a project who's sole job is to copy binaries.

fix typos in features .md files

Merge from future into features/patterns

Also up the ulimit on Linux during restore (#10768)

Downgrade Editors to a released version of LanguageServices and add it and AppDesigner to ProjectSystem.sln

Conflicts:
	src/Debugging/Microsoft.DiaSymReader.PortablePdb/Microsoft.DiaSymReader.PortablePdb.nuspec
	src/Dependencies/VisualStudio/project.json
	src/NuGet/Microsoft.CodeAnalysis.Common.nuspec
	src/NuGet/Microsoft.Net.CSharp.Interactive.netcore.nuspec
	src/NuGet/Microsoft.Net.Compilers.netcore.nuspec
	src/Scripting/Core/Scripting.csproj
	src/Tools/CommonNetCoreReferences/project.json
	src/VisualStudio/Core/Def/ServicesVisualStudio.csproj

Remove all project.lock.json files left over from a bad merge.

Merge stabilization into master

Remove references inherited via NuGet

This prevents us from needing to reference LanguageServices, Workspaces & CodeAnalysis when inside ProjectSystem.sln. We don't deploy package to output directory so we do not overwrite the "current" version of the assembly.

Updated ProjectSystem with new GUID of Composition.csroj

Update failing test.

These got out of sync.

Fix EnC for compilations with dependencies using time-based versioning