Load saved muway and set to muways soft threshold.

 * Fix for ticket:257
 * Updated nway code to save the soft threshold when saving.
 * Updated nway code to load the soft threshold when saving.
 * Updated MussaWindow.load code to use soft threshold loaded from muway file.
 * Upadted MussaWindow.load code to load properly when the window
   is empty to start with.
   * Added a reset() function to the ThresholdWidget to avoid emits
     * This actually didn't fix the problem (see ticket:262)
   * Broke the SIGNAL/SLOT loop causing multiple nways to be run, by
     breaking the connection from MussaWindow to ThresholdWidget while
     the ThresholdWidget.reset() function is called.