This enables most of the signals of GstRTSPClient
Only automatic bindings for now, which is enough to allow implementing a simple rtsp-server example. Depends on https://github.com/sdroege/gstreamer-sys/pull/8 Uses a new gir feature proposed at https://github.com/gtk-rs/gir/pull/539 to make doc regeneration easier. Fixes https://github.com/sdroege/gstreamer-rs/pull/80