This is the merging of the code that was previously in
/nmap-exp/david/nmap-massping-migration. These are all the big changes
that get rid of massping in favor of doing host discovery using
ultra_scan.
For now, there is a toggle that turns these new changes off. Undefine
NEW_MASSPING in targets.cc to go back to the old code. All of that will
be deleted eventually.
There are likely a few more changes that will be made to this system in
the near future. Those will be made in
/nmap-exp/david/nmap-massping-migration and merged back.
Don't release this just yet, because I'm going to make a few more
commits real quick to remove some debugging stuff.
(Note to self: this merge back was from r5693 in
/nmap-exp/david/nmap-massping-migration.)
