Re: WIP: RangeTypes

Another updated patch.

Improvements:

  * Full GiST support
    - Thanks to Alexander Korotkov for sending me a new picksplit
algorithm for my "temporal" project on pgfoundry. I modified it for use
with range types, including a (hopefully) intelligent way of handling
empty and unbounded ranges.

  * Quite a few tests added, some cleanup done

Open items:

  * naming issues:
    - period -> tsrange ?
    - periodtz -> tstzrange ?
    - intrange -> int4range
  * add int8range
  * Documentation improvements
    - CREATE TYPE
    - ANYRANGE
    - Data Types section
  * Thom Brown and Tom Lane pointed out that the type inferencing
    should be able to promote int4 to numeric for queries like:
      select '[18,20]'::numrange @> 19;
  * Should the SQL function length(), which relies on polymorphic "-",
    be marked immutable, stable, or volatile?
  * representation or alignment issues
  * parser should be improved to handle spaces and quoting better
  * Should btree_gist be pulled into core to make it easier to use 
    exclusion constraints with range types?
  * Typmod (optional)

Regards,
	Jeff Davis