OpenTracing

This library is a .NET implementation of the OpenTracing API. To fully understand this platform API, it's helpful to be familiar with the OpenTracing project and terminology more generally. For the time being, mild backwards-incompatible changes may be made without changing the major version number. As OpenTracing and opentracing-csharp mature, backwards compatibility will become more of a priority.

Adds OpenTracing instrumentation for .NET Core apps that use the `Microsoft.Extensions.*` stack. Instrumented components: HttpClient calls, ASP.NET Core, Entity Framework Core and any other library that uses DiagnosticSource events.

Adds OpenTracing instrumentation for .NET Standard apps that use GRPC.