Create grouping feature similar to UITableView

[techiemac]

It would be nice to have the ability, much like the current iOS UITableView to support grouping.

I realize this is a potentially double edge sword (i.e. it would be bad for it to degenerate into a giant tree grid which tend to have usability issues) :)

Depending on how deep I can get into the code, I hope to also take a stab at this myself and give back a bit to the project.