Changed to use only https (no more http).
All curl commands use '-k' for robustness.
Changed default install method to tarfile using the
consistently named sdp.Unix.tgz file name. Eliminated
'-t' flag; cloning is now done only when '-b' is used.
Removed command attempting to change ownership of
/hxdepots/reset dir to 'perforce' before that user
exists. Better if that folder remains root-owned
in any case, as only root can run it.