Enhancement and bug fix for Info plugin
Enhancement and bug fix for Info plugin

- added "Follow New" and "Raise New" checkbox controls at the bottom
  panel.  These are explained in the docstring.
- fixed a bug in which some information was not shown if there is no
  image loaded

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