title: Updating barplot in real time using pyqtgraph
body: <p>I am trying to create a little widget using pyqtgraph that updates in real time. I made this work with no problem using a line plot. However, I would like to do this with a bar plot using the <code>addPlot</code> method in <code>pg.GraphicsWindow</code>.</p>
  
  <p>Here's the basic setup I have so far:</p>
  
  <pre><code>import pyqtgraph as pg
  
  self.win = pg.GraphicsWindow(title='Spectrum Analyzer')
  self.spectrum = self.win.addPlot(
              title='SPECTRUM', row=1, col=1
          )
  
  # Plot the init data -- I want this to be a bar plot
  self.obj = self.spectrum.plot(pen='m', width=3)
  
  # Update data content in plot -- stick in loop
  self.obj.setData(data_x, data_y)
  </code></pre>
  
  <p>I like the rapid features of <code>addPlot</code> and would rather not use <code>pg.plot().addItem(pg.BarGraphItem())</code> in a loop due to high latency.</p>