relax SVN archive

Updated the relax API documentation at http://www.nmr-relax.com/api/ for relax version 3.1.0.

The new http://www.nmr-relax.com/api/3.1/ documentation has been started.

Updated the relax HTML manual at http://www.nmr-relax.com/manual/index.html to version 3.1.0.

Updated the http://www.nmr-relax.com/download.html webpage for relax version 3.1.0.

Changed the version number to 3.1.0.

Backported the relax 3.1.0 CHANGES file addition to trunk.

The command used was:
svn merge -r21689:21690 svn+ssh://bugman@.../svn/relax/tags/3.1.0 .

Updated the CHANGES file for relax 3.1.0.

Added the relax 3.1.0 user manual to the repository.

relax version 3.1.0.

This is a major feature release which adds full support for the analysis of relaxation dispersion
data.

Bug fix for the previous commit (r21686).

Improvements in the test_suite.clean_up.deletion() function.

It is now more fail safe on Python 3 by completely avoiding the WindowsError checking.