Table demos with changes to scala.swing.Table.

TableDemo, TableSelectionDemo, TablePrintDemo, and TableFTFEditDemo.
SimpleTableDemo and SimpleTableSelectionDemo are withheld because the Integer
valued columns are not properly editable.

Changes to scala.swing.Table: columnCount, fillsViewportHeight, various print
functions, selectionModel, columnModel, defaultEditor.  The print functions,
especially, need review.

```
println(s"Setting value at $row,$col to $value (an instance of ${value.getClass()})"
```