Do not offer 'var' if it would cause overload resolution issues.

* Separating warning messages for constant filter expression
* Deal with try-catch with finally block and add test

Use all RIDs on all platforms

Add the Roslyn version string into Help > About

Disable 'use local function' in a few important language cases.

RunCore previously had a mix of diagnostic reporting methods including
lists of Diagnostics, lists of DiagnosticInfos, ConcurrentQueues of
Diagnostics, and just printing things directly to the console. This
commit tries to simplify things by moving to using Diagnostics and
DiagnosticBags wherever possible in the compile+emit phase of RunCore.

Simplify check.

Fixed field name generation in Introduce constant field refactoring

Fixed NRE in IntroduceVariableCodeRefactoringProvider refactoring

Insert documentation comments in the face of trim_whitespace

This shows our informational version in Help > About instead of a
useless ProductID GUID.

Fixes dotnet/roslyn#17038.

scripting hosts: print the submission stack trace only to the console

Merge master to post-dev15.5-contrib

It turns out the BaseNuGetRuntimeIdentifier is still needed on two
projects which are not fully converted to the new SDK. Moving the
property to those specific projects. It will go away once they are
converted to the new SDK.

Fix PathMapping to a root directory

The old package had a bug in RunCsc.cmd that didn't properly
quote the dotnet path. When the SDK is upgraded to a sufficient
version by VS, the full dotnet path will be used, which contains
spaces and fails without proper quoting. This updates us to a package
which contains almost the same compilers, but includes the fix for
quoting the dotnet path properly (in PR #23034).

The trim_trailing_whitespace can affect tokens to the right of the caret
so we need to check the token to the left.

Fixed IntelliSense completion for initializing a generic class member when a class member has the same name as generic type argument

Reduce memory allocations in NamingStyle.Capitalize/DecapitalizeFirstLetter

Merge remote-tracking branch 'dotnet/master' into merges/master-to-post-dev15.5-contrib-20171109-080019

* dotnet/master: (33 commits)
  Minor PR feedback.
  Ensure that we track additional member symbols in the VB binder conte… (#23077)
  Address final feedback.
  LCS GetDistance optimization for large differences in sequence lengths (#23081)
  Fix compilation errors after merge.
  Fix typo.
  Small typo fix, add a couple of more tests.
  Fix spelling typos.
  Small refactor.
  Exclude mid statements from compound assignment.
  Add proper In and OutConversion support to C# for ICompoundAssignmentOperation.
  Trivial renames of IOperation API parameter names
  Extract conversion and binary operator logic into reusable components, and refactor all instances to use it.
  Rewrite IPlaceholderOperation to IConditionalAccessInstanceOperation when in that context.
  Fix bug in making GetReceiverOperation static.
  Added test for static With statements and shared fields as RValues.
  Make CreateReceiverOperation return a lazy.
  Fix tests broken after merge.
  Fix the operation verifier code now that getoperationinternal no longer exists.
  Added asserts for static instances.
  ...

Fixed issue with missing suggestion to import namespace if class contains a property with same name as the extension method.