Changes include:

1. Enhance CompilationWithAnalyzers to allow computing analyzer diagnostics for a specific tree/span within a compilation and/or for a subset of analyzers. Implementation ensures no duplicate analysis by tracking partial analysis state and caching the reported analyzer diagnostics.

2. Overview of the new APIs added to CompilationWithAnalyzers:
    1. GetAnalyzerSyntaxDiagnostics(tree, analyzers, ct)
        1. Analogous to SyntaxTree.GetDiagnostics(ct)
        2. Gets analyzer diagnostics reported by executing syntax tree actions on the given tree.
    2. GetAnalyzerSemanticDiagnostics(semanticModel, spanOpt, analyzers, ct)
        1. Analogous to SemanticModel.GetDiagnostics(spanOpt, ct)
        2. Gets analyzer diagnostics reported by executing rest of the non-compilation actions on the given tree span.
    3. GetAnalyzerCompilationDiagnostics(analyzers, ct)
        1. Gets rest of the analyzer diagnostics which are reported by either of the following means:
            1. Compilation actions (and compilation end actions)
            2. Non-compilation actions reporting diagnostics on different tree: Executing a symbol action on a symbol definition in a tree, can report diagnostic on its partial definition in some other tree.

3. Simplify IDE analyzer driver by switching it to using the new CompilationWithAnalyzers APIs for analyzer diagnostic computation. Both the IDE and compiler drivers now use the compilation event queue model for driving analysis.

"Roslyn" -> "Microsoft" or "Microsoft.CodeAnalysis"

At the moment, these aren't used by any completion providers in the features layer. Until we decide that this is ready to support cross-platform, let's keep them in the editor features layer closer to the providers that actually use them.

- apply feedback: unify C# and VB

A large change again, mostly mechanical. There's a fair amount to clean up and that will come in the next commit.

This change touches a lot of files but most of the changes are
mechanical. Essentially, this introduces a CompletionItemRules type as a
means to customize the behavior of a CompletionItem. This will
ultimately be the home of several methods that currently reside on
CompletionListProvider (such as IsCommitCharacter and
IsFilterCharacter), but only the SendEnterThroughToEditor method has
been moved in this change. Other methods will be moved in future
changes.

* Convert the ICompletionProvider interface to a CompletionListProvider abstract class.
* Rename CompletionItemGroup to CompletionList
* Introduce a CompletionListContext type to be used by providers to specify the contents and
  details of CompletionLists with a RegisterCompletionListAsync() method.
* Change GetGroupsAsync() method to GetCompletionListAsync(), which returns Task<CompletionList> rather
  than Task<IEnumerable<CompletionList>>.
* Move code that merges, de-dupes and sorts completion lists from the controller into the
  completion service. This affected a few VB spell check unit tests which now change their ordering
  slightly.

This moves all of the InternalsVisibleTo which were defined in code into
the project files where the majority of the IVT definitions lived.

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.

Currently, the C# and VB suggestion mode completion providers both implement ICompletionProvider
in nearly the same way. This change introduces a new base class containing the shared
implementations.

Note: prior to this change, C# and VB returned different values for IsCommitCharacter: false and
true respectively. Now they'll both return false. However, this is OK because the completion
controller handles builder completion items specially and IsCommitCharacter so that is never
actually called in this case.

now user has a easy way to see just errors from build. the content should be exactly same as what output build window shows.

this change set also includes several misc changes such as adding support for error source and build tool.

Make constructors of FixAllContext public and add a new nested abstract public type "FixAllContext.DiagnosticProvider" for fix all diagnostic queries.

This unblocks a few product/test FixAll scenarios, see #2709 for details.

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.

We now look at the identifier names in an effort to find the IErrorType symbol that triggered the diagnostic. Once we find the error symbol we return the assembly identity assuming that this is the correct error symbol since we can't filter by MissingMetadataTypeSymbol.

The compiler does not generate semantic errors inside lambdas in the
presence of syntactic errors causing several features to not work in
lambdas with syntax errors.  The bug for this
([1867](https://github.com/dotnet/roslyn/issues/1867)) was moved to
milestone 1.1 so we are going to use an analyzer in the interim for 1.0.

1. We now check for IncompleteMemberSyntax nodes and
LambdaExpressionSyntax nodes which contain syntax diagnostics on any of
their descendant nodes.
2. We report both unbound identifier names and constructors that the
compiler reports as binding, but which fail overload resolution
(actually don't exist).

Performance considerations should be mitigated by only doing these
checks only lambdas with syntax errors.

Other notes:

- Renamed analyzer to UnboundIdentifier instead of AddImport since it is
being used in more places than just the AddImport fixer
- Updated the DiagnosticDescriptor for this analyzer to take
localizeable strings.

Fixes #1744
Fixes #1241
Fixes #1239

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

now, error list will have column (which is off by default) that shows source of each errors in a
format "assembly name" for analyzers node. and "assembly name" [vsix name] for vsix

Fixes internal TFS bug 1142095

Commit any existing rename session when a document is saved or when
debugging run mode is entered. This ensures rename sessions are
completed before Edit and Continue sets the buffers to readonly when
debugging begins or when break mode is exited.

previously we made system to prefer live diagnostic over build diagnostic.
also when we merge those two, we used very detail info to find out build and live diagnostics are same or not.

but the issue was diagnostics from build didn't have all information live one has, also diagnostics from build is static
when live one is changing as user type in IDE. which lead to race where build diagnostic might be already out-dated on arrival.

new system is that we prefer diagnostic from build over live. and don't distinguish them by detail info but whether live can produce
same diagnostics build produced. as user change file, we will replace build diagnostics in affected files to live diagnostics.

this should remove chance where build diagnostic got stuck in the system until next build. and as user change files, live diagnostic
over take build diagnostics.

first, made solution crawler options to show up in Roslyn/Option pane to make experiement easier.
second, tweaked the way higher/normal/low priority processor interact each other.
last, made solution crawler to pick next project to process a bit smarter.

misc.
fixed an issue where lazyLogmessage didn't clear cached message correctly
changed etw logging default to not log at all

this is a fix for a watson crash

Fixes #249: Fix IDE diagnostics test framework to use DiagnosticAnalyzerService to compute diagnostics rather than DiagnosticAnalyzerDriver.

This change serves multiple purposes:
1) Makes our test framework consistent with the IDE scenario in fetching diagnostics. We have missed out on multiple regressions where the core IDE DiagnosticAnalyzerDriver does the right thing and hence the tests pass, but the DiagnosticService in IDE does additional filtering and certain diagnostics are not reported in VS. This change should avoid such bugs.
2) Enable testing for diagnostics V2 engine work that JohnHamby is doing to merge IDE and compiler analyzer drivers. For this engine, there is no IDE driver and hence existing IDE diagnostics tests can't be run. This change should enable running IDE diagnostics on V2 engine.
3) Move a whole bunch of of test only code in DiagnosticAnalyzerService_Test.cs into the test layer.

other ones such as build will have minimum length of 0 for squiggles since they are not updated as your types. minimum length of 1 for such squiggle just makes it look like staled squiggles.

now code fix should support diagnostics from compilation end action.

a few options are added to test experience which can be changed from Tools/Options/Roslyn/Diagnostic pane.

This reverts commit b37052d0.

more clean up after feedback

all tests passing. now StateManager owns all state related operation.

and added place holder for state manager