Added skeletons for services and clients
Services work, but can't use class members as request handlers
Skeleton compiles. Callback dispatching works
Added ids to requests and clients. Use promises and futures to synchronize req/res calls
Req/res wiring done. Compiles and does NOT CRASH
Both server and client work. Service's response channel is still created in create_service, should be created when responding. There is an issue with copying response objects. Added async_call to client, which returns a future.
talker/listener and service examples compile
checkin
compiles
Everything compiles again
Client example works
Removed unused header
Added synchronous call method
Added note about GCC 4.6
Merge branch 'services' of github.com:osrf/ros_dds into services
Finish move of AddTwoInts messages into rclcpp_examples package.