relax SVN archive

Added a comment to the output from value.display and value.write to describe the parameter.

This idea is discussed at http://thread.gmane.org/gmane.science.nmr.relax.user/1428.

The idea is to take the parameter description from the specific analysis API and add it to the top
of the file or output. This is to help understand what the Rex value are. For example for the Rex
parameter the first line would be:

# Parameter description: Chemical exchange relaxation (sigma_ex = Rex / omega**2).

Merged revisions 18839 via svnmerge from
svn+ssh://bugman@.../svn/relax/trunk

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r18839 | bugman | 2013-03-17 11:23:00 +0100 (Sun, 17 Mar 2013) | 6 lines

Backported the relax 2.2.4 CHANGES file to trunk.

The command used was:
svn merge -r18837:18838 svn+ssh://bugman@.../svn/relax/tags/2.2.4 .
........

Updated the news links on http://www.nmr-relax.com/download.html for relax version 2.2.4.

Updated the download webpage http://www.nmr-relax.com/download.html for relax version 2.2.4.

Updated the relax API documentation (http://www.nmr-relax.com/api/) to version 2.2.4.

Updated the relax HTML manual to version 2.2.4.

This will appear at http://www.nmr-relax.com/manual/.

Added the relax 2.2.4 PDF manual to the repository.

Updated the version number to 2.2.4.

Backported the relax 2.2.4 CHANGES file to trunk.

The command used was:
svn merge -r18837:18838 svn+ssh://bugman@.../svn/relax/tags/2.2.4 .

Updated the CHANGES file for relax 2.2.4.