Fiji macro scripts for generation of distance maps

generate_distance_map.ijm: generate a distance map from a backbone
image generated by the dataset tools. It generates maps where the
centerline pixels is marked with 0 and increase up till a set level.
Background is marked by value 255.
image_to_results.ijm: dumps the active image pixel by pixel to a
results table with it coordinates and corresponding intensity value
(for export to CSV later).