Allows to use an unpatched (!) PDELab 2.0 for the multidomain
applications. Users have to upgrade to PDELab 2.0 and the 2.0 release
branch of dune-multidomain. 

- Subdomain GridFunctionSpaces are expected to use
  Dune::PDELab::NoConstraints instead of
  ...NonoverlappingConformingDirichletConstraints. Users have to remove
  the corresponding property settings in the subproblem files.

- Subdomain GridOperators are no longer needed. The property name has
  been removed from subdomainproperties.hh. Users have to remove
  the corresponding property settings in the subproblem files.

- Use OrderingTags instead of Mappers.

- The storage of residual, current and old solution in the
  assembler/model uses shared_ptr now. 

- The components of the multidomain vector containers are accessed via
  the base() method. Everything in splitandmerge.hh still relies on
  EntityBlockwiseOrdering. 

Reviewed by gruenich.



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@13287 2fb0f335-1f38-0410-981e-8018bf24f1b0