Query results in grid, new patch

Attached is a newer version of my query results in a grid patch. This
version adds a custom table class to store the data. My quick testing on
WinXP shows this patch to display query results in about one half the time
my previous patch did. That patch, at least on my system, in turn
displayed results in about one half the time the old code did. So at least
on WinXP, this patch will result in results displaying in approximately
25% of the time they previously took.

The table class I created contains the bare minimum functionality I needed
to make it work. To help improve the speed, I designed the class to use as
few memory allocations as possible.

As with the previous patch, there are still focus issues that make the
clipboard support flakey. The issue seems to be the grid control doesn't
seem to hold onto the focus the way the old list object did, making it
difficult to decide which object should handle a Copy request. I don't
know very much about wxWidgets, so I'm stumped on the issue. Someone else
will have to help out.

Ed