Big O changes, this time. Some more constant factors, too.
Big O changes, this time. Some more constant factors, too.

 * Use a spatial tree for the "stay" records and query it. Note that I
   said "changes", not improvements. It's 1:30 in the morning, so I'll
   leave the benchmarking to others. (:
 * Also, build the list of gone-overlap, come-overlap, come and gone
   records "right" the first time around, so we can just return it
   unmodified, without having to mapcar (list x x) over them first.

slyrus/mcclim,swflint/McCLIM,onixie/mcclim,onixie/mcclim,antifuchs/mcclim,antifuchs/mcclim,onixie/mcclim,slyrus/mcclim,swflint/McCLIM,swflint/McCLIM