Add *.pxd files to source distribution
Add *.pxd files to source distribution

This is important when the package is first bundled as a source
distribution and then installed:

    python setup.py sdist
    pip install dist/PyMAD-<version>.tar.gz

pymad/cpymad,pymad/cpymad,pymad/jpymad,pymad/jpymad,pymad/jpymad