Fixing buggy query to get list of warps and stacks. It would return a row for every stack that exists, rather than a row for every skycell/filter combination. Completely re-crafted the query so that it returns a single row for each skycell/filter combination, with the number of warps available to be stacked and the number of warps in the biggest stack. It's a bit complicated, and I'm not entirely sure it's 100% correct, but it seems to work on the simtest (though that's only a single skycell).