Merge dev15-rc2 into master

Add StorageLocations for Outlining and Structure-Guide options.

Add a small amount of support for Expression-Bodied properties in CodeModel.

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.