We introduce a "ref type" for use in declarations

and complete adjustments due to last (incomplete) merge from master.

Add support for the new async find refs.

Tiny cleanup tweaks to 'remove doc comment node'.

A code fix for a set of Documentation Comment diagnostics returned by the compiler

Overhaul syntax model for deconstruction decl

Remove extraneous IVT...

added initial etw logging to code

wouldn't that be annoying to notice after we've shipped?

Revert "Insert traces for cases.."

this will be used to improve perf

Addresses #12347 

Dynamic Analysis method spans for methods with attributes, instrumentation of bound pattern switch statements

This reverts commit b18139a6.

Similarly for TupleDeconstructionVariableDesignation.
Also found many places to handle both kinds of foreach statements.

* MetadataVisualizer: Display table for nil handles

* Harden Literal helpers against bad metadata

* Add support for embedded pdb

This reverts commit ffa21e50.

* Implement source link feature

* Fix CommonCompiler to open source link stream, add E2E tests

* Reduce code duplication across VB and C#

Merge dev15 preview 4 into master20160804 225700

Move type to file: offer outer.inner.cs pattern on nested types

Change hard coded xunit reference to use MSBuild prop