Data Scrubber

I have (finally) implemented a data scrubber for the spot database. It currently handles several situations:

1) identifying and deleting bogus spots (bad callsigns)
2) bogus timestamps (delete if too old or fix if odd-minute report)
3) remove duplicate spots of same station on same band by a reporter, such as those caused by power line noise in tx or rx (it keeps the strongest report in a given time slot)

It always saves a copy of the original spot before deleting or modifying it in case I need to put the data back. About 1.5-2% of spots are being removed or fixed so far.

The scrubber is currently set to run on the 2-week recent history once per day. At some point soon, after I get it doing band-fixing where possible, I will run it on the entire database history. If you have ideas for other data integrity checks, please let me know!