refinement:
- LOCAL: Local grid refinement as you would expect it
- COPY: As local, but unrefined elements are copied along to the next
        level.  That way each level completely covers the computational
	domain.
- COLLAPSE: After refinement, the grid is collapsed into one single
        grid level.

You can change the refinement mode at any time using the methode
setRefinementType().

[[Imported from SVN: r1216]]