relax SVN archive

Added many small details to the release checklist document.

This is for the formatting and editing of the CHANGES file, which is used for the release
announcements. Some additional details about the API documentation at http://www.nmr-relax.com/api
have been added too.

Small improvement for the devel_scripts/log_converter.py script for detecting commit boundaries.

Completed the relaxation dispersion model list at http://www.nmr-relax.com/analyses/relaxation_dispersion.html.

Started to expand the http://www.nmr-relax.com/analyses/relaxation_dispersion.html webpage.

Updated the news announcement link for relax version 3.1.0 at http://www.nmr-relax.com/download.html.

The correct link is https://gna.org/forum/forum.php?forum_id=2421.

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 .