Global Using Directive
=========================

The *Global Using Directive* feature extends using directive syntax with an optional `global` keyword that can precede the `using` keyword.
The scope of Global Using Directives spans across all compilation units in the program.  

Proposal: https://github.com/dotnet/csharplang/blob/master/proposals/GlobalUsingDirective.md

Feature branch: https://github.com/dotnet/roslyn/tree/features/GlobalUsingDirective

Test plan: https://github.com/dotnet/roslyn/issues/51307
