UUID datatype progress

Folks,

During past days I have been coding the UUID datatype which has been fun
and great learning curve for me. Here is the current progress:

- basic i/o functions are done.
- various records for pg_class,pg_operator,pg_amop etc, are added
- the additions pass the regression check :)
- btree and hash indexes go as expected (as far as I could test)
- currently 3 inputs and 1 general output are supported
(as suggested by Tom)

remaining uuid todo list:
- binary receive and send functions are yet in development.
- Additional testing, testing and again testing.
- cast and convert functions have to be done
- develop some kind of a new_guid() function (if required)
- develop a SERIAL like type (has to be discussed yet)

If everything goes okay, I should be able to submit a beta patch for
reviewing during next two weeks (and get shot at :))

Regards,
Gevik