No longer complain if we cannot find both torify and tsocks. As long as
we have one we are happy.
Do not rely on which, it's not POSIX.
Catch error if torsocks fails and print an error message.
Update Torify to use torsocks by default and to warn when the user is
using the older tsocks program. Update torify and the torify man page
to refelect changes to torify. Add warnings in both.
