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
* @param viewer
	 */
	private void setupEditingSupport(final int columnIndex, ViewerColumn viewer) {
		if (getCellModifier() != null) {
			viewer.setEditingSupport(new EditingSupport() {
				/*
				 * (non-Javadoc)
				 * 
				 * @see org.eclipse.jface.viewers.EditingSupport#canEdit(java.lang.Object)
				 */
				public boolean canEdit(Object element) {
					return getCellModifier().canModify(element,
							(String) getColumnProperties()[columnIndex]);
				}
				/*
				 * (non-Javadoc)
				 * 
				 * @see org.eclipse.jface.viewers.EditingSupport#getCellEditor(java.lang.Object)
				 */
				public CellEditor getCellEditor(Object element) {
					return getCellEditors()[columnIndex];
				}
				/*
				 * (non-Javadoc)
				 * 
				 * @see org.eclipse.jface.viewers.EditingSupport#getValue(java.lang.Object)
				 */
				public Object getValue(Object element) {
					return getCellModifier().getValue(element,
							(String) getColumnProperties()[columnIndex]);