title: "Segmentation Fault" in matplotlib running example Librosa script
body: <p>After many issues I've installed Librosa (<a href="https://github.com/librosa/librosa" rel="nofollow">https://github.com/librosa/librosa</a>) on Linux Mint 18 Mate x64. When I want to run example script, e.g.: <a href="http://librosa.github.io/librosa/generated/librosa.feature.tempogram.html#librosa.feature.tempogram" rel="nofollow">http://librosa.github.io/librosa/generated/librosa.feature.tempogram.html#librosa.feature.tempogram</a>, it crashes with "Segmentation Fault" error:</p>
  
  <pre><code>$ python librosa-feature-tempogram-1.py 
  /usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_qt5.py:140: Warning: g_main_context_push_thread_default: assertion 'acquired_context' failed
    qApp = QtWidgets.QApplication([str(" ")])
  Segmentation fault
  </code></pre>
  
  <p>I've tried to debug it line-by-line and there is result:</p>
  
  <pre><code>$ python
  Python 2.7.12 (default, Jul  1 2016, 15:12:24) 
  [GCC 5.4.0 20160609] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import librosa
  
  &gt;&gt;&gt; # Visualize an STFT power spectrum
  ... 
  &gt;&gt;&gt; import matplotlib.pyplot as plt
  &gt;&gt;&gt; y, sr = librosa.load(librosa.util.example_audio_file())
  
  &gt;&gt;&gt; plt.figure(figsize=(12, 8))
  /usr/local/lib/python2.7/dist-packages/matplotlib/backends/backend_qt5.py:140: Warning: g_main_context_push_thread_default: assertion 'acquired_context' failed
    qApp = QtWidgets.QApplication([str(" ")])
  Segmentation fault
  </code></pre>
  
  <p>Probably there is some issue with matplotlib library and Qt (5.7.0). Moreover, I remember I had many issues when installing Librosa, including matplotlib, so it could be some installation issue. However, I don't know how to solve it. I hope somebody will have helpful clues for me.</p>