ENH:  Add interrupt button near progress bar.
      Implement help button.
      Implement cancel button.
      Add scrollable output window.
      Replace ON/OFF & combobox editors with checkboxes.
      Tab/backtab in cache table jumps between values (not names and values)
      Add tooltips to show help strings.
      Add application icon and qtmain for Windows.

BUG:  Fix save of cache values on configure.