Add wrapper for Pk.DLocalFiniteElements.
For 1d,order1 this currently maps to p11d

[[Imported from SVN: r162]]
Implemented RefinedP1LocalFiniteElement in 3d.
For 1d the Basis functions are also implemented, but p21d/pk1d is still missing.
Thanks to Uli Sack for this patch!

[[Imported from SVN: r163]]
Test RefinedP1 for 2d and 3d seperately

[[Imported from SVN: r164]]
Added test for RefinedP1LocalFiniteElement.
Notice that this test needs dune-grid and ALUGrid

[[Imported from SVN: r165]]
Ignore executable of new test

[[Imported from SVN: r166]]
Ups, only tested pk3d with order 1 before.

[[Imported from SVN: r167]]
Pass constructors for variants in 2d and 3d.
It would really be nice to have the same interface.

[[Imported from SVN: r168]]
Match interface of Pk2D constructor with Pk3D constructor

[[Imported from SVN: r169]]
Add some docu for Pk3D constrcutor

[[Imported from SVN: r170]]
Document constructors of LFE classes. You will in general use these.

[[Imported from SVN: r171]]
*document constructor for variants
*remove special 2d constructor
 if you want to use it you know that you have
 Pk2DLFE and can use this class
*mimic variant constructor for 1d
 only for a consistent interface
 this does aktually nothing since you don't need to flip in 1d
 (even if Pk1dLFE would exist)

[[Imported from SVN: r172]]