Show the time zone in :info; replace ctime with strftime
This fixes trac-#146.
The new function owl_util_time_to_timestr takes a const struct tm *
instead of a const time_t because, although we pass around time_t for
just about everything else, this lets the caller decide whether to use
localtime or gmtime (UTC).
Note: I'm not sure that "%c" (which is locale-dependent) will always
include the time zone. If not, or if we want a bit more consistency, we
can switch to something like "%a %b %d %H:%M:%S %Y %Z" (like "Fri Jul 22
15:39:45 2011 EDT") or "%a %b %d, %Y %h:%M:%S %p %Z" (like "Fri Jul 22,
2011 03:39:45 PM 2011 EDT") or something. On linerva, "%c" seems to be
equivalent to "%a %d %b %Y %h:%M:%S %p %Z" (like "Fri 22 Jul 2011
03:39:45 PM EDT").
