title: how to set python environment variables
body: <p>I've slowly been working my way through all of the dependencies required to get PyTables installed. That included updating Numpy, install numexpr and cython and the hdf5 libraries. </p>
  
  <p>I am now getting an error that states it cannot find a local HDF5 installation. It states that I should set an HDF5_DIR environment variable. I have created a windows environment variable HDF5 and HDF5_DIR, and I've added the hdf5 bin directory to my path. Still no joy.</p>
  
  <p>Is there a separate set of environment variables for python? I suspect there is, but searching for python and environment variable just leads to LOTS of descriptions of how to set up PYTHONPATH.</p>