GetNearestTrackHull now also does an exact match only, if searchDir == 0.

src/MATLAB/+Helper/GetNearestTrackHull.m

 % [hull hullTime] = GetNearestTrackHull(trackID, time, searchDir)
-% Search track for a non-zero hull nearest to the specified time, searchDir
-% beack in time if searchDir < 0 or forward if searchDir > 0. Returns 0 if
-% no hull exists in specified direction.
+% 
+% Search track for a non-zero hull nearest to the specified time, 
+% (searchDir < 0) -> search back in time,
+% (searchDir > 0) -> search forward in time,
+% (searchDir == 0) -> search exact time only.
+% returns hull=0 if search fails.
 
 function [hull hullTime] = GetNearestTrackHull(trackID, time, searchDir)
     global CellTracks CellHulls
@@ -10,7 +13,7 @@ function [hull hullTime] = GetNearestTrackHull(trackID, time, searchDir)
     hullTime = 0;
     
     hash = time - CellTracks(trackID).startTime + 1;
-    if ( hash < 1 && (searchDir >= 0) )
+    if ( hash < 1 && (searchDir > 0) )
         hull = CellTracks(trackID).hulls(1);
         hullTime = CellHulls(hull).time;
         return;