revert to OO interface (no pyplot) in OO example

Author: ivanov

examples/api/agg_oo.py

@@ -6,10 +6,12 @@
 from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
 from matplotlib.figure import Figure
 
-fig, ax = plt.subplots()
+fig = Figure()
+canvas = FigureCanvas(fig)
+ax = fig.add_subplot(111)
 ax.plot([1,2,3])
 ax.set_title('hi mom')
 ax.grid(True)
 ax.set_xlabel('time')
 ax.set_ylabel('volts')
-fig.canvas.print_figure('test')
+canvas.print_figure('test')