Warn if ports are specified in {Socks,Dir}Policy

We have ignored any ports listed here since 80365b989 (0.0.7rc1),
but we didn't warn the user that we were ignoring them.  This patch
adds a warning if you put explicit ports in any of the options
{Socks,Dir}Policy or AuthDir{Reject,Invalid,BadDir,BadExit}.  It
also adjusts the manpage to say that ports are ignored.

Fixes ticket 11108.
Clarify default behavior of {SOCKS,Dir}Policy harder

Improvement on 11108 fix; suggested by cypherpunks.
Merge branch 'bug11108'