Loosened the chi2 check in the Relax_disp.test_korzhnev_2005_15n_mq_data system test.

This is to allow the test to pass on a 32-bit Linux (Mageia 1) test system.
Backported the relax 3.1.2 CHANGES file addition to trunk.

The command used was:
svn merge -r21967:21969 svn+ssh://bugman@svn.gna.org/svn/relax/tags/3.1.2 .