#4 Label features further along a route

[Stephen Battey]

New intersection processor to find features further along the line.
3 possible algorithms to find features further along the line (need performance test to show which is quicker):
1. Buffer the line. Intersect the buffered line with the features.
2. Buffer the features. Intersect the buffered features with the line.
3. Use the vivid solution's DistanceOp class to compute the distance from the line to each feature (this distance can be re-used when computing the distance to that feature from the edge of the map).