Unsigned int functions

Hi,

I finally seem to have my unsigned int2/int4 types working correctly,
but will wait until 7.1 is out of the door, and test a bit more, before
resubmitting.

A question though:

I've put in functions (as copied from the int2/int4 implementation) that
implement operators for differently typed arguments, e.g. uint2*uint4.
This saves the type conversions, but adds to the number of functions in
the system.

When sorting out the constant problems, I realised that (uint2,uint4)
combinations will probably be very rarely used, while (int4,uint4)
combinations will be much more common, i.e. when there are constants
involved.

Question is: should I add these functions? Are we looking at too much
bloat, i.e. should I replace the (uint2,uint4) combinations with
(int4,uint2) and (int4,uint4)? Lots of combinations are possible, but I
do not have a good feel for the trade-offs.

I only wanted unsigned ints, so that we could develop and test stuff on
postgres before moving it onto Tandem. So please let me know what you
think the correct trade-offs are and I will implement it and resubmit
the patch.

Cheers,

Adriaan