relax SVN archive

Fixes for the Scientific python parts included with relax for the module path.

The 'extern' package is now a proper package - the __init__.py file has been added!

Removed Scientific python from the dependency checking.

Modified the Scientific python PDB reader relax module to use the internal module.

Removed Scientific python from the information printout from 'relax --info'.

The Scientific python PDB reading tests are no longer skipped if the module is not installed.

Added the PDB reading parts of Scientific python to relax.

This is allowed as the CeCILL licence is GPL compatible. The Scientific python website is
https://sourcesup.cru.fr/projects/scientific-py/, but it hasn't been updated in a long time and
might be a dying project. Therefore the code is now part of relax so it can be used in the future.

Some fixes for the subprocess.Popen() calls on MS Windows.

Updates for the diffusion tensor optimization sample script.

The problem was identified (for sample script "dasha.py")
by Shantanu Bhattacharyya <shantanu01 att cmu dott edu> in the post at
https://mail.gna.org/public/relax-users/2011-05/msg00018.html (Message-id:
<7a068ac7a9e90b8e8d374b334a20d4be.squirrel@...>).

Updates for the Dasha sample script.

The problem was identified by Shantanu Bhattacharyya <shantanu01 att cmu dott edu> in the post at
https://mail.gna.org/public/relax-users/2011-05/msg00018.html (Message-id:
<7a068ac7a9e90b8e8d374b334a20d4be.squirrel@...>).