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.

qutil/plotting/live_view.py

@@ -1487,6 +1487,9 @@ class LiveView2DBase(LiveViewBase, abc.ABC):
 
             self.axes['line'] = self.fig.add_subplot(gs[1, 0], sharex=self.axes['main'],
                                                      label='line')
+            self.axes['line'].yaxis.set_tick_params(which='both', left=True, right=True,
+                                                    labelright=True, labelleft=False)
+            self.axes['line'].yaxis.set_label_position('right')
             self.axes['line'].set_yscale(norm_to_scale(self.img_kw.get('norm')))
             self.axes['main'].label_outer()
             # Indicate that the line plot is the lowest axes to be used for labeling
@@ -1700,7 +1703,7 @@ class IncrementalLiveView2D(LiveView2DBase):
     Plot the last acquired 1d trace as well:
 
     >>> view = IncrementalLiveView2D(put_data, autoscale='yc', plot_line=True)
-     >>> view.start()
+    >>> view.start()
     >>> plt.pause(0.1)  # Only here for doctest
 
     Stop the event loop: