The distance-speedup branch will be used to try out ways to speed up spatial operations, starting with the code provided by V. Basupalli in 2010. This first checkin adds a new object that just acts as a passthrough to the existing R-tree search. This new object will be a place where we can put a cache in between the callers and the R-tree search.
Checked in original "memoization table" code sent on Mar 22 2010.
Changes to make memoization.[ch] compile: Changed uses of HRD_herd_t to UNT_unit_t. Removed DEG_TO_RAD macros because they were conflicting with the ones used in gis.c. Removed some unused variables.