Substitute description of Meyer's flooding algorithm with Bertrand's text.

Add links to watershed sites.
Remove unnecessary code.

All voxels are visited and marked, so none can have an INIT value after the flooding.
Add missing javadoc comments.
Rename "showResult" method to something closer to its actual function.
Simplify code to update display when changing from border to object image.
Add "-gradient" to the output title only if the gradient is shown.
Add "-gradient" to the output title only when displaying overlays.
At the watershed with priority queue and dams, make dam all unlabeled voxels.

This creates very small plateaus but only when single voxels are surrounded by dams, and therefore need to be set as dams as well.
Add methods to record and call the new GUI components from macros.

TODO: register/call gradient radius and algorithm.