Show or hide the clipping text edit box depending on whether the current
selection is a clipping, empty clipping, or folder
Styling improvements to Clippings Manager.  Get rid of unneeded horizontal line
below the main toolbar, and get rid of border on <splitter>
Clippings Manager UI refresh:
- Get rid of unneeded UI labels for clipping name and description textboxes
- Show placeholder text in empty edit box for clipping text
- Don't show shortcut key field and link to shortcut key list if the current
  selection isn't a clipping
- Don't allow unnamed clippings or folders - substitute with a default name
New UI strings for default clipping and folder names, and placeholder text for empty clipping text edit box