*REPOST* update of contributed IP and MAC types

Hope you don't mind my marking something that's for the contrib
directory with *REPOST* like this, but Marc did ask us to, and I
did post this back on Februaray 1, so...

I'm including an update to my user defined IP and MAC address type
implementation that's in contrib/ip_and_mac/.  This one works right
with 6.3, avoids the problems I ran into earlier with LIKE, and
includes a bit of extra functionality.

Here's an idea for the TODO list, by the way: make it doable without
resorting to black magic to make a user defined type indexable!  :-)

-tih
-- 
Popularity is the hallmark of mediocrity.  --Niles Crane, "Frasier"