Convert FakeSign to a NuGet reference

Fixed an errant bad line ending

Delay-load Roslyn services

Commit bcb2c8c7 added an `[Import]` of `IDiagnosticAnalyzerService` to
our Solution Explorer code. Unfortunately, this causes us to compose and
load effectively all of Roslyn whenever the Solution Explorer is opened,
even if no C# or VB code is loaded.

The fix is to delay pulling in the `IDiagnosticAnalyzerService` until we
actually need to make use of it, which is guaranteed to be after we have
loaded a C# or VB project (and thus we've already loaded Roslyn).

Qualify member accesses with type name in nameof

Fixes #1193

During expansion, directly accessed members need to be qualified with
"this." or "TypeName.". Prior to this change, we always qualified
instance members with "this." and static members with "TypeName.", but
this technique fails in nameof contexts where an instance member can be
referenced from a static method, resulting in an improper "this."
qualification. We can only legally use "this." when both the member
being accessed and the context from which we are accessing it are
non-static. However, this change updates the expanders to always use
"TypeName." qualification in nameof contexts regardless of the
staticness of either member because it is always legal and feels more
natural in nameof expressions (where no actual value is being accessed).

Handle unsupported diagnostics reported by analyzers.

Fixes #252 : If an analyzer reports a diagnostic with an unsupported diagnostic ID, i.e. no descriptor returned by SupportedDiagnostics has that ID, then throw an ArgumentException in ReportDiagnostic method. This exception would be turned into an analyzer diagnostic by the driver and reported back to the analyzer host.

Also fix a few tests that were reporting diagnostics with unsupported ID!

Fixes #252 : If an analyzer reports a diagnostic with an unsupported diagnostic ID, i.e. no descriptor returned by SupportedDiagnostics has that ID, then throw an ArgumentException in ReportDiagnostic method. This exception would be turned into an analyzer diagnostic by the driver and reported back to the analyzer host.
Also fix a few tests that were reporting diagnostics with unsupported ID!

Sort nodes by location before determining contiguous spans encompassed b...

CommonSyntaxNodeExtensions.GetContiguousSpans() was incorrectly assuming that the supplied nodes will be in the order in which they appear in source. This helper is used in the analyzer that produces diagnostics to grey out unused usings (i.e. to produce one diagnostic for a set of contiguous unused using directives).

Due to the above incorrect assumption, we would end up producing a single diagnostic spanning multiple unused usings sometimes and multiple diagnostics at other times. Often different invocations of the analyzer for the same source file would produce different set of unused usings diagnostics.

While this does not cause observable problems in regular usage - this is a problem for tests and led to flaky behavior where test would pass sometimes and fail at other times.

VB EnC: enable editing methods with lambdas and LINQ - merged

Use TryGetValue when looking up cached SyntaxContexts

Use Unicode escape sequences for control characters

Make the IsLowPriority API take a cancellation token as well.

Changes to the syntax associated with BoundQueryBody caused slight changes in error span of some rarely reported errors. Update tests.

Conflicts:
	src/Compilers/CSharp/Portable/Syntax/SyntaxUtilities.cs
	src/Compilers/VisualBasic/Portable/Lowering/LambdaRewriter/LambdaFrame.vb
	src/Compilers/VisualBasic/Portable/Symbols/AnonymousTypes/AnonymousTypeManager_Templates.vb
	src/Compilers/VisualBasic/Portable/Syntax/SyntaxUtilities.vb
	src/Compilers/VisualBasic/Test/Emit/CodeGen/CodeGenClosureLambdaTests.vb
	src/EditorFeatures/VisualBasicTest/EditAndContinue/ActiveStatementTests.vb

Preserve Key modifiers from existing anonymous type properties

Fixes #1292

Make the IWorkCoordinatorPriorityService async and appropriately cascade out the asynchrony.

Originally this was synchronous because it was used through codepaths that all were
inherently synchronous.  Over the last year the WorkCoordinator has become increasingly
async, and we're now at the point where this API can be async too.  This is a win for
TypeScript because we have to currently implement this API in blocking fashion.  This
has shown up in profiles, and making it async should be a nice win for us.

Handle using static

Responding to PR feedback, fixing some typos and simplifying some of the
boolean logic.

Fixed crash in ValidateUnsafeParameters when binding lambdas for error r...

Remove a line which was only present for internal debugging purposes.

Make the portable ResultProvider DLLs portable

Lately our developer builds have gotten a bit flaky due to the
dependency on FakeSign.  This is both a tool we create and consume
during build.  In order to do this properly every tool which depends on
FakeSign should list it as a dependency.  This ensures it will be built
before the project which consumes it.

Unfortunately this is not the case.  Virtually nothing lists it as a
dependency and hence we are often broken during build due to ordering
issues.  This fixes the problem by hosting FakeSign as a NuGet package.

Note: the long term plan is to have the compiler support oss signing
directly from the command line.  At that point the majority of our
projects will employ fake / oss signing via a command line switch.  The
FakeSign tool will still be necessary for IL projects like Concord
though hence this is not wasted work.

We created the CoreSystem projects to ensure that we wouldn't take
dependencies on non-portable APIs.  Now that the ResultProviders are
really portable, they enforce this requirement directly.

Prior to this commit, they were identical to the corresponding desktop
(i.e. NetFx20) assemblies but now all the pieces are in place to compile
them as portable assemblies.

Cleverness: Move resources into the portable projects and link them into
the corresponding desktop projects.  The desktop projects can compile
portable designer files, but not vice versa.