Note that this version is probably identical to two versions ago.

Add extra include file for aix to find endian information.

 including arguments allowed.

 having to modify the system-wide library database.

Define constants to allow day of week decoding.
Add new datetime and timespan routines.

Remove older date and time code (retain NEW_DATE_CODE and NEW_TIME_CODE).
Use common encoder for date and time.
Fix datetime +/- timespan math bug.

 This is compatible with abstime formats.

 #defines.

Add timezone info to abstime2tm().

 This allows use of the DateStyle session variable.

 This matches the behavior of the original formatting for abstime.
Repair datetime + timespan date arithmetic for year boundaries.
 From patch submitted by Dave Skinner.

 datetime +/- timespan. Only manifested when date is at end of month
 and time pushes the date into the next month.