[Dune] The UG-Unitcube in the Grid tutorial

[Oliver Sander]

Hi Dune!
As proposed by Andreas earlier today I started removal of the AmiraMesh
code from the grid tutorial.  The 2d grids are directly created now.
For the 3d grid this would also be possible, albeit rather lengthy.
Since the rest of the tutorial is surely using DGF we may as well
use it for the 3d UG unit cube as well.  Since I don't know how to
use it, though, someone else would have to do that.

--
Oliver

************************************************************************
* Oliver Sander                ** email: sander at mi.fu-berlin.de        *
* Freie Universität Berlin     ** phone: + 49 (30) 838 75217           *
* Institut für Mathematik II   ** URL  : page.mi.fu-berlin.de/~sander  *
* Arnimallee 6                 ** -------------------------------------*
* 14195 Berlin, Germany        ** Member of MATHEON (www.matheon.de)   *
************************************************************************