Remove serialization from Features layer

A few of the ENC types were marked as [Serializable] so that they worked within custom debugger visualizers. This change adds custom serialization to the debugger visualizers so that the types no longer need to be marked as [Serializable].

Clean up Interactive Exports/ContentTypes...

These changes should prevent us from prematurely loading the Interactive
dlls when opening a C# project (before the Interactive Window is open).

Un-redirect Console.Out at the end of each test

Dramatically speed up generation of metadata as source for large types

Remove more ReadLines.

Remove ReadLine from AsyncWithShortCircuiting003

...so that it doesn't wait indefinitely.

Stop throwing unreachable exceptions in AddImport codefix provider.
Fixes #4395 and internal bug 1188340

Before this change, showing MAS for a type with 4000 empty methods took about 2
minutes on my machine. With this change, it now takes 2-4 seconds. There were
2 different issues causing the slow generation:

1. When formatting the generated file, the formatting engine needs to find the
distance between every token and the new line (or start of file)  before it.
This calls  TokenStream.GetOriginalColumn, which computes the original column
by walking backwards through its list of tokens counting the width of tokens
and trivia until it finds a newline. Though this n ^ 2 operation takes place
in all invocations of the  formatter, it is normally ameliorated by the fact
that real code has enough newlines that GetOriginalColumn doesn't actually
traverse back to the first token in the file. Generated files have no newlines,
so GetOriginalColumn takes up about half the time of generating a MAS document,
because GetOriginalColumn is called on every token in the file.
To mitigate this, we augment MAS' custom formatting rule to not calculate
anchor indentation. Anchor indentation is what requires the original columns,
but no operations are produced for MAS documents, which have no newlines
in them.

2. If instructed to use "auto insertion location", the code generation service
computes the location to insert each member, one at a time. This computation
checks that the type's members are sorted, resulting in n ^ 2 iterations over
the list of members. The fix for this takes Kayle's fix for enum members a
little further:
When instructed not to use "auto insertion location", the code generation
generates declaration syntax for each member without inserting it. It then
sorts that list of declarations once, and bulks adds them (essentially
appending each declaration to the end of the growing type declaration).

I've fixed up some of the "Create*Declaration" methods to match the behavior
of the corresponding "Add*Declaration" methods.

Remove InteractiveWindow._projectionSpans

Remove src/Diagnostics/ from dotnet/roslyn repo

Conflicts:
	src/InteractiveWindow/EditorTest/InteractiveWindowTests.cs

Change our public API tracking

Handling anonymous delegate case, fixes #4598

Add tests for cut and copy

Report a diagnostic if an analyzer reports a diagnostic with an invalid ID.

Fixes #4376 

Conflicts:
	src/InteractiveWindow/EditorTest/InteractiveWindowTests.cs

Add exception filters to make crash dump analysis easier

Ensure that casts resuling in explicit numeric conversions are not suggested as redundant in C#

Do not emit a type test for exception object to be an object when the…

Fixes invalid codegen in a case if a readonly field is spilled on the…

Do not insert newlines into what is probably a single-line construct.

Conflicts:
	src/InteractiveWindow/Editor/InteractiveWindow.cs
	src/InteractiveWindow/Editor/ReplInput.cs

Ensure that VB parenthesis simplification works for XML elements and XML empty elements

Fix C#/VB Inline Temporary Variable for interpolated strings that are target-typed to FormattableString

Fixes #4620