The exec_program fuction is deprecated use execute_process instead.
Use the FindBoost config file which is installed by Boost instead of the CMake
module.
Fix one cmake_minimum_required version by defining also a maximum version.

This version is an exact copy of the last revision of the trunk branch
of the old SVN repository of CbmRoor at
https://subversion.gsi.de/cbmsoft/cbmroot/trunk
The old SVN repository will still be available for read access.