Begin removing VSL name from build system

Disable Use Object Initializer diagnostic prior to C# 3

Fix casing of resource string.

fail fast when extension manager is null

fix error list navigation

made us to crash right away when extension manager is null to get better info on the situation.

if extension manager is null, vs is seriously broken.

fix https://devdiv.visualstudio.com/DevDiv/_workitems?path=Assigned%20to%20me&_a=query

in preview 5, error list navigation behavior has changed. this tweak roslyn side to accommodate the behavior change.

bug - https://devdiv.visualstudio.com/DevDiv/_workitems?id=284073&_a=edit

Merge dev15-rc into master

Report better telemetry for fix-all code actions.

Fixes: #13911

Non recursive tree serialization

Strip off underscores when generating constructors from fields.

Fixes #14219

SuggestedAction/CodeAction cleanup

Make GenerateType work off of an Incomplete-Member.

Fixes #13211

VSL is a name no longer relevant to Roslyn.  Begining it's removal.

This change needs to be comitted first so I can clean up some internal code.

More build file updates

Make Microsoft.Build.Tasks.CodeAnalysis an independent DLL

Revert manifests

Currently, when a local function is captured inside another local
function or lambda it can capture 'this' without generating a frame.
This is useful, but when that lambda is itself captured then the
capturing closure must also capture the frame pointer, namely 'this'.
Currently, local function frame pointers are not correctly captured when
the captured local function itself captures something from a "higher"
scope than the capturing local function.

This change solves this problem by:

1) Considering a local function's captured variables when deciding its
scope. If the local function captures variables from a higher scope,
that local function will be analyzed as belonging to the "higher" scope,
causing that local function to register for frame capturing.

2) Since the proxies for capturing frames are not available at the time
of local function reference rewriting, the proxies must be saved. There
is a new temporary bound node for this purpose,
PartiallyLoweredLocalFunctionReference, that stores the proxies and the
underlying node for later use during the rewriting phase. This node
should never make it past LocalFunctionReferenceRewriting.

When these steps are completed, local functions should act very
similarly to all other captured variables with different frames, where
the frame pointers are captured and walked in a linked list in order to
access the target with the proper receiver/frame pointer.

This reverts commit 8115c019.

This reverts commit 514dc656.

added parse option to vb compilation option

missing parse option in compilation option caused some vb My types to fail.

Add pre-requisites section to vsix manifests

Fixes #14740

Don't crash if you rename a file and change or remove the extension