title: PyCharm does not recognize modules installed in development mode
body: <p>I have two pure python projects in PyCharm 3.4.1 Professional Edition. The first one, let's call it <code>p</code> (like package), is structured as a setuptools package (i.e. with setup.py, all requirements etc., however it is not uploaded to pypi or any other online repository). The second one, let's call it <code>s</code> (like script), is just a python script along with two modules.</p>
  
  <p>Project <code>s</code> is (in PyCharm) configured to use a dedicated virtualenv, let's call it <code>venv</code>.</p>
  
  <p>The problem I have is the following: when I install the project (package) <code>p</code> in <code>venv</code> like this:</p>
  
  <pre><code>$ source /path/to/venv/bin/activate
  (venv)$ cd /path/to/p
  (venv)$ python3 setup.py develop
  </code></pre>
  
  <p>in PyCharm in project <code>s</code>, <code>import p</code> statements are errorneous with message <em>No module named p</em>. However, when I run the script in <code>s</code>, everything is fine, the only problem is the PyCharm IDE complaining about not being able to find the module. I can live with this but it is very annoying...</p>
  
  <p><s>Why does this happen? Is it a PyCharm thing or packaging related thing?</s> See <strong>NEWS</strong> below.</p>
  
  <hr>
  
  <p>The project/package <code>p</code> has the following structure:</p>
  
  <pre><code>p/
  |
  +- p/
  |  |
  |  +- __init__.py
  |  +- other subpackages, modules, etc.
  +- setup.py
  +- README, DESCRIPTION, setup.cfg, etc.
  </code></pre>
  
  <p>When I configure the PyCharm project <code>p</code> to live in its own virtualenv and install it there in development mode, everything works fine.</p>
  
  <hr>
  
  <p><strong>NEWS</strong></p>
  
  <p>This problem is still present in PyCharm 5.0.4. However, I managed to solve it, kind-of.</p>
  
  <p>For some reasons I had to install another package from pypi. I did it through PyCharm by going to File -> Settings -> Project:  -> Project Interpreter, there clicking on the green <code>+</code>, finding the package and pressing the Install Package button. After the installation, the package installed by <code>python3 setup.py develop</code> is well recognized by PyCharm. Obviously the problem was that PyCharm didn't have some cache in sync with reality.</p>
  
  <p>So the new question is, can PyCharm be told to update its caches regarding the used python environment?</p>