ptrace shouldn't require root

[doy]

We control spawning the nethack process, so we should be able to instead spawn the ptrace tracer program, and have it fork, call PTRACE_TRACEME, and then exec nethack, and have the tracer communicate back via a named pipe rather than via stdout. I'm not sure what the best solution for dtrace would be, although I don't think converting the ptrace code to work on OSX would be that big of a deal either.