--Wrote (nearest-obstacle point lexicon) that returns the name of the nearest obstacle to the given point and (distance-factor point obstacle lexicon) that returns 1 if the obstacle is closest, else 0.5--just guessed at this factor for now, might need to change it later.
--Modified my one-object preposition functions to accept the lexicon as an additional argument in order to call (distance-factor ...) inside their lets.  Also modified the call to the one-object preposition evaluator from within (score-parse ...).
--Put in dummy definitions for new obstacles and prepositions as placeholders.
--Tested (produce-score-matrix ...) with changed preposition functions and output looks reasonable.  Need to examine a little more closely to ensure the right sentences are winning for the runs we have.