#2 Basic Grid: Implement basic grid sorting on column headers

[Larry Rix]

Design, build and test basic grid sorting using header mouse clicks and accelerator keys (shortcut key strokes).

Primary Use Case:

1. Column starts in natural order.
2. Click #1 --> Column sorts in ASCENDING order. Appropriate down arrow symbol displayed.
3. Click #2 --> Column sorts in DESCENDING order. Appropriate up arrow symbol displayed.
4. Click #3 --> Column returns to natural order.

Alternate Use Case:

1. Other column previously sorted in ASCENDING or DESCENDING order.
2. Click #1 --> Other column sorts to natural order, then apply Primary Use Case to Current.

Generate tests to prove the sorting.