* Added support for client interceptors, which can be configured through
Client constructor's interceptors parameter. Interceptors will be
executed by Client.$createStreamingCall and Client.$createUnaryCall.
Using interceptors requires regenerating client stubs using version 19.2.0 or
newer of protobuf compiler plugin.
* Client.$createCall is deprecated because it does not invoke client
interceptors.
Split the large client/server.dart files into smaller pieces. This is in
preparation for splitting the HTTP/2 dependencies into a separate file
and make it easier to implement other transports.
Zbigniew Mandziejewicz