New features

• Grpc.Net.Client targets .NET Standard 2.0 (#1118)
• Grpc.Net.Client.Web targets .NET Standard 2.0 (#1203)
• gRPC client retries (#1187)

Changes

• Change gRPC client factory to set HttpHandler (#1183)
• Change some RequestStream.WriteAsync errors to match Grpc.Core (#1199)

Fixes

• Fix response stream errors not updating call status (#1198)
• Fix deadline timer rescheduling because of timer precision (#1201)
• Fix client not raising HTTP diagnostic source events (#1211)