Deleted an unused function.
Deleted another unused function.
Make sure to close a connection to any deleted database
Improved the debug output so that you can see which subclass of spatial_search_t object (memorization table or R-tree) is being called.
Fixed a bug in the process of selecting between recipient units that are exactly the same distance from the source of exposure. Checkin includes a new test case that shows the bug.
Merge branch 'master' into distance-speedup