Fix for an issue with Preferences plugin
Fix for an issue with Preferences plugin

- fixes an issue where some saved settings may not be available if
  you restart the program with different options.  This fix insures
  that the plugin correctly builds the GUI anyway

ejeschke/ginga,ejeschke/ginga,pllim/ginga,naojsoft/ginga,naojsoft/ginga,pllim/ginga,pllim/ginga,ejeschke/ginga,naojsoft/ginga