This changes our generic-lowering logic to use 'Arity' instead of
'IsGenericType' to figure out whether or not a local function frame
needs generic subsitution. We previously used IsGenericType, which is
inappropriate because it also considers whether or not the containing
type of the frame is generic. The containing type is necessarily already
subsituted when calling a local function, so it will never be possible
to substite type parameters.

Instead, we should use Arity of the frame, which is only non-zero if the
frame itself is generic, regardless of the containing type.

Build changes

Update tests to use multiline literals.

Fixes #14785

Fixes #14825

Merge dev15-rc into master

Fixing up our targets / settings file

Also clean up some grammar in Syntax.xml
Fixes #14651

Fix root path being truncated when formatting errors

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

Then I better merge quickly.  ;-)

If it makes it in, great, if not then I guess we'll just get it in RC.2.