Add live_view module to qutil.plotting.

The live_view module provides a matplotlib interface for concurrent data viewing using animations and blitting. For line plots without axis rescaling, frame rates of ~100 fps can be reached. A 1080x1920 pixel image can be displayed at ~20 fps. Data sources are pushed to a background thread from where they can fill a queue.

See mjolnir commits a771a5cc..205318e6 for earlier history.