Merge branch 'bump-version-to-2.10' into 'master'

dune.module: bump version to 2.10-git

See merge request !491

dune.module

 Module: dune-istl
-Version: 2.9-git
+Version: 2.10-git
 Author: The Dune Core developers
 Maintainer: dune-devel@lists.dune-project.org
 Description: Iterative solver template library which provides generic sparse matrix/vector classes and a variety of solvers based on these classes