This seems like a good place to stop for the day...

Tons of stuff added today:
1.  Delete button is now added to the grid, and its event handled, and
wired up to the deletion function of the data API.
2.  Deletion is now implemented at the API level.  User code can call
deleteWithRecord or deleteWithPK on the data source object, and the data
source should handle this, and then throw a "recordDeleted" event when
it's done.  The record collection is hooked up to this event when it's
created, and thus gets notified when it fires.
3.  Deletion function is now sort of implemented on the ODataDataSource.
Unfortunately, the proxy page I'm using doesn't support the DELETE verb,
so it doesn't work yet, but I think it probably would if it didn't need
a proxy.  This is at the top of the to-do list for tomorrow.