title: Pycharm does not recognize Cython modules located in path
body: <p>I have these two lines of code:</p>
  
  <pre><code>from libc.stdlib cimport malloc, calloc, realloc, free
  
  from optv.tracking_framebuf cimport TargetArray
  </code></pre>
  
  <p>The first one is not highlighted by PyCharm (2016.2.3 professional on Ubuntu 14.04) as unresolved refference but the second line is highlighted in red underline as unresolved refference.</p>
  
  <p>My <code>TargetArray</code> class is located in <code>tracking_framebuf.pxd</code> file which is located in <code>/usr/local/lib/python2.7/dist-packages/optv/</code> along with .c, .pyx, .so files with the same name.</p>
  
  <p>I inserted <code>/usr/local/lib/python2.7/dist-packages/optv/</code> and <code>/usr/local/lib/python2.7/dist-packages/</code> paths to be associated with python interpreter, but the error messages are still apearing in the editor.</p>
  
  <p>Despite the error messages the file (along with others) is cythonized successfully using this setup.py script:</p>
  
  <pre><code># -*- coding: utf-8 -*-
  from distutils.core import setup
  from Cython.Distutils import build_ext
  from Cython.Distutils.extension import Extension
  
  import numpy as np
  import os
  inc_dirs = [np.get_include(), '.']
  
  def mk_ext(name, files):
      return Extension(name, files, libraries=['optv'], include_dirs=inc_dirs,
          pyrex_include_dirs=['.'])
  
  ext_mods = [
      mk_ext("optv.tracking_framebuf", ["optv/tracking_framebuf.pyx"]),
      mk_ext("optv.parameters", ["optv/parameters.pyx"]),
      mk_ext("optv.calibration", ["optv/calibration.pyx"]),
      mk_ext("optv.transforms", ["optv/transforms.pyx"]),
      mk_ext("optv.imgcoord", ["optv/imgcoord.pyx"]),
      mk_ext("optv.image_processing", ["optv/image_processing.pyx"]),
      mk_ext("optv.segmentation", ["optv/segmentation.pyx"]),
      mk_ext("optv.orientation", ["optv/orientation.pyx"])
  ]
  
  setup(
      name="optv",
      cmdclass = {'build_ext': build_ext},
      packages=['optv'],
      ext_modules = ext_mods,
      package_data = {'optv': ['*.pxd']}
  )
  </code></pre>
  
  <p>Am I missing something on my way to get rid of these error messages and being able to view the contents of the .pxd files i place in the path?</p>