Fix for bug #20921 (https://gna.org/bugs/?20921), the GUI tests freezing in MS Windows.
The problem was that the dipolar interaction wizard in the model-free auto-analysis GUI element was
calling its user functions asynchronously. This can lead to racing conditions. The commit r80084
(http://article.gmane.org/gmane.science.nmr.relax.scm/17840) somehow randomly triggers this racing
on MS Windows systems only together with the Mf.test_mf_auto_analysis GUI test. Now all user
functions are called synchronously.
