CLHEP 2.4.4.0 installation

with respect to previous versions, there is not anymore .configure script. 
Thus, after having created build and install directory inside a clhep directory (in home),
which in its turn contain also the source files of the library, type the following commands:

$ cd <build_directory>
$ cmake -DCMAKE_INSTALL_PREFIX=<install_dir> <source_code_dir>
$ cmake --build . --config RelWithDebInfo
$ ctest
$ cmake --build . --target install

The above will configure the build, compile CLHEP libraries with optimization and
debugging symbols, run the test suite and finally install the CLHEP binaries and
headers under the chosen install prefix.