Dr. Jekyll version 0.9b

No new features, indeed. Since 0.9a we have implemented some new
features, but we fixed some bugs as well. The most interesting is
probably the Region Of Interest (ROI) stuff. At the moment this is
only used for limiting operations to a 2D slice, but the ROI can be
any subset of the cube. We also plugged the mother of all memory
leaks, and added help texts to a lot of the windows and plugins.