#2 Virtual KTable

[Kresimir Tonkovic]

One thing I'm missing in KTable is the ability to have
a virtual sorted table. KTableSortedModel is well
suited for use on data that is all in memory. Some of
my datasets are large and I need the ability to respond
to clicks on the fixed cells by changing the order
clause of my selects and refreshing only the data that
is currently on screen.

The included patch implements this. The
KTableSortedModel is turned into an interface, which
allows the implementation to handle sorting in an
arbitrary manner. The old KTableSortedModel is moved to
DefaultKTableSortedModel, with the specific method of
sorting elements in memory. KTableSortComparator is put
inside KTableSortedModel.

The ExampleGUI seems to work well with these changes.

[Kresimir Tonkovic]