Conservative refactoring: dis.box[][] is accessed in (i,j) raster
coordinates, significantly saving space. dis.box2pixel(r,c) is called
before accessing dis.box[i][j]. Later refactoring will define
the box as a separate object, and the Vertex r, c as its own object.
Basic tests pass. Some of the diagnostic messages were removed as
these clutter the code--these should be moved into their own objects.