relax SVN archive

Updated the download webpage http://www.nmr-relax.com/download.html for relax version 2.2.1.

Modified the relax manual subtitle as this is no longer only for relaxation analysis.

Fix for the news forum link http://gna.org/forum/forum.php?forum_id=2375 for relax 2.2.0.

The 2.0.0 download links now point to http://www.nmr-relax.com/download_request.html.

These files are no longer stored on the Gna! servers so cannot be download from
http://www.nmr-relax.com/download.html.

The 1.3.16 download links now point to http://www.nmr-relax.com/download_request.html.

These files are no longer stored on the Gna! servers so cannot be download from
http://www.nmr-relax.com/download.html.

Added the relax 2.2.1 PDF manual to the repository.

Changed the version number to 2.2.1.

Updated the release checklist to include the devel_scripts/log_converter.py script usage.

Merged the relax version 2.2.1 CHANGES file back to trunk.

The command used was:
svn merge -r18365:18366 svn+ssh://bugman@.../svn/relax/tags/2.2.1 .

Updated the CHANGES file for version 2.2.1.