Update ANSI INTERVAL section:

< * Add support for ANSI time INTERVAL syntax, INTERVAL '1 2:03:04' DAY TO SECOND
< * Add support for ANSI date INTERVAL syntax, INTERVAL '20-6' YEAR TO MONTH
< * Process mixed ANSI/PG INTERVAL syntax, and round value to requested precision
<
<   Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS INTERVAL
<   MONTH), and this should return '12 months'
<
< * Interpret INTERVAL '1:30' MINUTE TO SECOND as '1 minute 30 seconds'
> * Add ANSI INTERVAL handling
> 	o Add support for day-time syntax, INTERVAL '1 2:03:04'
> 	  DAY TO SECOND
> 	o Add support for year-month syntax, INTERVAL '50-6' YEAR TO MONTH
> 	o Process mixed ANSI/PG syntax, and round value to requested
> 	  precision or generate an error
> 	o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS
> 	  INTERVAL MONTH), and this should return '12 months'
> 	o Interpret INTERVAL '1:30' MINUTE TO SECOND as '1 minute 30 seconds'
> 	o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))