"~" is resolved by the local shell (dumb me!). We now get the
destination directory by connecting to the first alive host from the
hosts' list (using cluster-ping), and get the user's home directory.
This is not perfect because it assumes the home directory is the same on
each host.
We could add an option in the future to do the test on each host, but
this would be significantly slower. Alternatively, we could allow to use
scp instead of pscp (because scp is smart enough to get the remote
user's home directory by itself), transferring files once at time, but
again, it would be slow.
The login was hard-coded to root, this was fixed to use by default the
local login name. The option -l was added to allow to specify a
different login name.