Add support for regions when using Langevin MD, following the approach
of Kantorovich et al, 2008. 4 new regtests added. (Lianheng Tong)


git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@13597 bac0169d-1eea-4375-b5f6-f89d2ced9994