Unsigned ints

Hi,

I know I'm a bit early to submit stuff for 7.2, but attached is a patch
(agains 7.1RC1) to add uint2 and uint4 as new types. I haven't put in
all the possible combinations of signed and unsigned ints as arguments
to operators -- I was going insane just doing it for all combinations of
uint2 and uint4. If anything is missing, please let me know and I'd
appreciate it if somebody could do some sanity checking on the patch, as
this is the first time I've actually inserted a new type into the
catalog.

Also, some other databases (Compaq Himalaya) use

SMALLINT UNSIGNED
INTEGER UNSIGNED

for these types. Dunno whether a type consisting of 2 words is going to
break the parser completely. If there are any problems with the patch,
please let me know as well -- not sure I've built it in the correct way.

Regards,

Adriaan