Bug 166236 [Viewers] ViewerColumn needs a dispose method
ViewerColumn adds a listener to its label provider which is never removed. We need a dispose method that removes the listener. Furthermore, if the column's label provider wraps a non-column-specific label provider, the viewer is already listening to it and the viewer column shouldn't. Must be fixed before the next I build.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewer.java
* way of editing values in a column viewer.
	 * </p>
	 * 
	 * @param editors
	 *            the list of cell editors
	 * @since 3.1 (in subclasses, added in 3.3 to abstract class)
	 * @see ViewerColumn#setEditingSupport(EditingSupport)
	 * @see EditingSupport
	 */
	public void setCellEditors(CellEditor[] editors) {
		if (viewerEditor != null) {
			viewerEditor.setCellEditors(editors);
		}
	}
	/**
	 * Sets the cell modifier for this column viewer. This method does nothing if editing
	 * is not supported by this viewer.
	 * 
	 * <p>
	 * Since 3.3, an alternative API is available, see
	 * {@link ViewerColumn#setEditingSupport(EditingSupport)} for a more flexible
	 * way of editing values in a column viewer.
	 * </p>
	 * 
	 * @param modifier
	 *            the cell modifier
	 * @since 3.1 (in subclasses, added in 3.3 to abstract class)
	 * @see ViewerColumn#setEditingSupport(EditingSupport)
	 * @see EditingSupport
	 */