#43 TabularData display should be sorted by indexing keys

[Jess Holle]

TabularData should be sorted by indexing keys rather
than dumped out in hash order.

The hash order of the Object[] keys produces a rather
useless ordering making result of interest harder to
find. Each indexing column is a Comparable or is
easily converted into a Comparable and thus the first
indexing column should be used as a primary key, the
second as a secondary key, etc.

This sorting may not be applied by default, but an
"Apply Sorting" button should be provided.
Column-header sorting should also be available (hence
the necessity of an Apply Sorting button to reapply the
original sorting).