title: Cython: Import definitions from .pyx file
body: <p>I have 1 Cython .pxd file and 1 Cython .pyx file, the pyx file contains a <code>cdef</code> class:</p>
  <pre><code># myclass.pyx (compiled to myclass.so)
  cdef class myclass:
     pass
  </code></pre>
  <p>Now is the .pxd file of another feature</p>
  <pre><code># another.pxd (with another.pyx along)
  from libcpp.vector cimport vector
  import myclass # This line is funny, change 'myclass' to whatever and no syntax error
  
  cdef vector[myclass] myvar # COMPILE TIME ERROR
  cdef myclass myvar2        # SIMPLER, STILL COMPILE TIME ERROR
  </code></pre>
  <p>When compiling another.pyx, Cython shows error about <code>vector[myclass]</code>, it says 'myclass' is unknown. Why is it so?</p>