Add StorageLocations for Outlining and Structure-Guide options.

Merge dev15-rc2 into master

make document and syntax changed as high priority changes.

Check that the project being enabled for pushing events to workspace …

Do not qualify static methods in delegate creations.

Fixup pattern we look for before offering ?.

Add 'throw' keyword ot the completion list in certain contexts.

Don't offer to inline variables if it would cause them to no longer be definitely assigned.

Don't offer UseObjectInitializer unless the ObjectInitializer is directly on the right of the =

2 can happen if a document's text has changed.

added missing cancellation token to Task.Delay

check command line mode before starting solution crawler and remote h…

Update 'add missing reference' to use the newly exposed compiler API.

Fixes https://github.com/dotnet/roslyn/issues/15245

Merge dev15-rc2 into master

I didn't make whole language service to not start since I wasn't sure end result of
such big change. that probably should be done by IDE team.

Provide an API to get unreferenced assembly identities obects from the diagnostics reported about them.

Make BatchFix code action application deterministic.

Add fixed version of Newtonsoft.Json

Introduce a new, deterministic BatchFix application algorithm. The new algorithm works in the following manner:

When producing code-actions, we keep track of both the code-action and the diagnostic that was used to create it. When we later go and 'apply' the code actions in a single document, we'll process them in diagnostic-location order. Is is as if we took each diagnostic of a document in order, produced the CodeAction for that diagnostic, and then applied that CodeAction.

I also took this opportunity to clean up and parallelize much of this code. We now compute code actions in parallel, and we process all documents in parallel when applying changes. Once all application is done, we can then take all the final results and apply them to the solution.