Replace standard by smart pointers for decoupled. This partially implements FS#182. Reviewed by Benjamin and Markus.

Dumux-Svn-Revison: 10177
Ported-By: Andreas Lauser <andreas.lauser@iws.uni-stuttgart.de>
Bugfix: It is wrong to use a shared_ptr for the TimeManager in OneModelProblem, std::since the object can be owned by a different class. This leads to a segfault at the end of test_transport. Therefore, a raw pointer is taken for the moment. We should carefully rethink this in general after the release. Discussed with Markus.

Dumux-Svn-Revison: 10278
Ported-By: Andreas Lauser <andreas.lauser@iws.uni-stuttgart.de>
Fixed bug in velocity output of decoupled 2p models

Reviewd by Klaus

Dumux-Svn-Revison: 10282
Ported-By: Andreas Lauser <andreas.lauser@iws.uni-stuttgart.de>
Bugfix: remove unnecessary null initializations of shared_ptrs which lead to compiler errors for gcc 4.3

Dumux-Svn-Revison: 10285
Ported-By: Andreas Lauser <andreas.lauser@iws.uni-stuttgart.de>
Bugfix: use Dune::stackobject_to_shared_ptr to correctly assign to a shared_ptr if the corresponding object is not owned. Found out by Markus.

Dumux-Svn-Revison: 10288
Ported-By: Andreas Lauser <andreas.lauser@iws.uni-stuttgart.de>