uuid patch 2.0 (8.3devel)

Folks,

Hereby the version 2.0 of the uuid datatype patch with modifications
commented by Neil.

- the uuid.h has been cleaned.
the declarations have been moved to uuid.c

- the text_uuid() and varchar_uuid() have been refactored.
- all uuid explicit functions are moved to uuid.c and made local.

* this patch has been tested on 8.3devel, the snapshot of 25-Jan-07

* this patch uses 28 new oids. I have assigned the oids from 2950.
If you need to change the oids, do not do this manually. I have a script
that does that. Just provide me 28 unused oids and I will generate a new
patch.

Please provide comments.

Regards,
Gevik