Organize includes.
Replace instances of conditional by Dune's SelectType.

The uses of conditional were unqualified and thus could not work.
Revert "Replace instances of conditional by Dune's SelectType."

Arg.  Didn't notice that conditional made it into dune-common meanwhile.

This reverts commit 8bbdaaeaf359845d011dd77affff23b61f06b813.
Replace deprecated GenericReference* by Reference*.
Add space between >> from templates because older compilers dislike that.
Merge branch 'p/gruenich/fixes'

Some fixes from Christoph. Thank you!

* p/gruenich/fixes:
  Add space between >> from templates because older compilers dislike that.
  Replace deprecated GenericReference* by Reference*.
  Add forgotten transition header for interiornodeconstraints.hh.
[stokesdg_vecfem]
make headercheck pass

- use the correct BC enum
- avoid shadowing template parameters
Merge remote-tracking branch 'origin/master' into p/gruenich/fixes
Remove unused typedefs.

They cause warnings by GCC 4.8.