Not all cleaned up yet.

Add text concatenation operator and function.
Add text trim function for SQL92 support.

Change definition for isreltime().
Change some names of #define constants to avoid conflicts with the yacc parser.

Used to support SQL92 compatibility.

Change box terminology from "length" to "width".
 Use length terminology in common with other geometric types (usually perimeter).
Fix bugs in line arithmetic which resulted in bad intersection calculations.
Deprecate temporary unstored slope fields.
Check explicitly for intersections at endpoints to avoid rounding ugliness.
Add center() routines for lseg, path, polygon.
Add distance() routines for circle-polygon, polygon-polygon.
Check explicitly for points and polygons contained within polygons
 using an axis-crossing algorithm. (Old code just checked bounding boxes).
Add routine to convert circle-box.
*whew*

Use standard decoder for isreltime().

Various compile errors concerning overflow due to shifts, unsigned, and bad prototypes, from Solaris, from Diab Jerius

As requested by Dr. Andrew C.R. Martin