Fix for several bugs in original PR
Fix for several bugs in original PR

- fixes for python 3
- "prefs" -> "settings"

stscieisenhamer/ginga,Cadair/ginga,naojsoft/ginga,Cadair/ginga,stscieisenhamer/ginga,rajul/ginga,pllim/ginga,pllim/ginga,naojsoft/ginga,rajul/ginga,rupak0577/ginga,stscieisenhamer/ginga,Cadair/ginga,pllim/ginga,ejeschke/ginga,rupak0577/ginga,naojsoft/ginga,ejeschke/ginga,ejeschke/ginga,rajul/ginga,rupak0577/ginga