rtspconnection: Add support for writing bufferlists and writing out via writev()
See #370 (closed) for the rationale.
What's left to be done
- Ognyan wants to update the last commit because it creates a circular reference (see #370 (comment 58337))
GLib MR for the
GOutputStreamAPI has to be merged https://gitlab.gnome.org/GNOME/glib/merge_requests/333