Address some minor TODO comments in features/ioperation branch

Add IOperation APIs for Dynamic invocations and indexer access

See https://github.com/dotnet/roslyn/issues/21385#issue-248857857

I also found that Range and Relational case clause have no tests in VB. Additionally, I also marked all OperationAnalyzerTests with CompilerTrait attribute so they don't get skipped in local trait based testing.
Fixes #22129

Merge master to features/ioperation

Changes to the IOperation API shape for loop statements

Update the 'add named arg' refactoring to support only adding to the current argument (for C# 7.2 and above).

guard us from build errors which are marked as CS or VBXXXX for a lin…

Merge master to features/ioperation

Disable useUserOverride in CultureContext

Remove InitialTargets=MakeCompilerScriptsExecutable

Merge `private protected` feature into master for C# 7.2 and VB 15.6.

Address feedback from Aleksey and generate a dynamic member reference expression for a bound method group that is a child of dynamic invocation

Merge master into privateProtected branch

Fixed Inline Temporary Variable refactoring

Updating some nuspec to list the correct framework requirements and dependencies.

Fix IArgument.InConversion/OutConversion

Merge master to features/ioperation

Merge master to features/ioperation

guard us from build errors which are marked as CS or VBXXXX for a linked file that doesnt belong to current solution we have.

this can happen for a project that is just added or already removed or project is added but design time build is not finished.

previously, that could crash VS, but now we will handle it gracefully.

we should now also maintain orders build error is reported.

Delete .Next projects

* Remove context (enclosing type name) from C# parser.
* Add a test demonstrating that unicode escapes are significant to determining if a method is a ctor.
This is a prerequisite to #367

Merge master into privateProtected

Fix up .gitattributes to clone .sh files with LF