Use boreas as alive scanner

Hi @tux,
the Boreas is the command line tool to scan for alive hosts. This command line client uses the libgvm_boreas library, part of gvm-libs. The openvas-scanner uses that library as well. You just have to enable it. Otherwise, it uses the classic method via a nasl script.
To enable Boreas for the openvas-scanner, you have to set test_alive_hosts_only = yes.
From the openvas man page:

              If  this  option  is  set  to 'yes', openvas will scan the target list for alive hosts in a separate process while only testing those hosts
              which are identified as alive. This boosts the scan speed of target ranges with a high amount of dead hosts significantly.