- node_runner: track all readers/writers in flow_resources vector,
release them via mxlReleaseFlowWriter/mxlReleaseFlowReader before
destroying the MXL instance (fixes 'leaked flow writer' warning)
- node_runner: remove_writer/remove_reader commands now also release
the MXL flow resources, not just reset the node's optional<>
- engine: call process_manager.stop_all(graph) on shutdown to kill
child node processes (prevents orphaned passthrough processes)
- graph: add get_node_mut() for process_manager to update node state
- process_manager: implement stop_all(Graph&) that SIGTERMs all
running node processes
- passthrough: reduce logging to first-grain and realign-once only
- tests: update flow format assertion to match NMOS
(urn:x-nmos:format:video instead of video/v210)
Johanness
4b50f49172