revisited copy implementations + resurrecting ViennaMini module

At this point the ViennaMini module merely loads 2d/3d Netgen meshes and
renders them.

copy.hpp contains a copy method, enabling the transfer from a ViennaGrid
segmentedmesh object to a VTK unstructured grid-based multiblock datastructure
--> atm no storage as a viennamos device on the central database
removed obsolete debug output