Rootmap creation enabled

The creation of rootmaps has been enabled. Two switches have been
added: --rootmap and --rootmap-lib, identical to the ones of the
genreflex version of root5.
Hard instead of soft links for genreflex & rootcint

The rootcling.cxx program behaves like rootcling or genreflex according
to its name. The soft link was replaced by a hard one in order to
activate this feature properly.