Calculating rollups for records where all children have been deleted

This is some awesome code; super helpful! I did notice that when it is used in a trigger and all of a master record's detail records are deleted, it does not calculate the rollups. This is because the aggregate query executes after the delete operation, and since it doesn't find any records at all, the AggregateResults loop never gets to it. I wrote a fix, if you're interested in merging it.